typedef struct SqlPreparedStmt SqlPreparedStmt;
struct SqlPreparedStmt {
  SqlPreparedStmt *pNext;  /* Next in linked list */
  SqlPreparedStmt *pPrev;  /* Previous on the list */
  sqlite3_stmt *pStmt;     /* The prepared statement */
  int nSql;                /* chars in zSql[] */
  const char *zSql;        /* Text of the SQL statement */


};

typedef struct IncrblobChannel IncrblobChannel;

/*
** There is one instance of this structure for each SQLite database
** that has been opened by the SQLite TCL interface.
................................................................................

  if( rc && rc!=TCL_RETURN ){
    sqlite3_result_error(context, Tcl_GetStringResult(p->interp), -1); 
  }else{
    Tcl_Obj *pVar = Tcl_GetObjResult(p->interp);
    int n;
    u8 *data;
    char *zType = pVar->typePtr ? pVar->typePtr->name : "";
    char c = zType[0];
    if( c=='b' && strcmp(zType,"bytearray")==0 && pVar->bytes==0 ){
      /* Only return a BLOB type if the Tcl variable is a bytearray and
      ** has no string representation. */
      data = Tcl_GetByteArrayFromObj(pVar, &n);
      sqlite3_result_blob(context, data, n, SQLITE_TRANSIENT);
    }else if( c=='b' && strcmp(zType,"boolean")==0 ){
................................................................................
  }
  zLine = realloc( zLine, n+1 );
  return zLine;
}


/*
** Figure out the column names for the data returned by the statement
** passed as the second argument.

**
** If parameter papColName is not NULL, then *papColName is set to point
** at an array allocated using Tcl_Alloc(). It is the callers responsibility
** to free this array using Tcl_Free(), and to decrement the reference
** count of each Tcl_Obj* member of the array.

























**
** The return value of this function is the number of columns of data
** returned by pStmt (and hence the size of the *papColName array).






















**











































































































































































































































** If pArray is not NULL, then it contains the name of a Tcl array
** variable. The "*" member of this array is set to a list containing
** the names of the columns returned by the statement, in order from

** left to right. e.g. if the names of the returned columns are a, b and
** c, it does the equivalent of the tcl command:
**
**     set ${pArray}(*) {a b c}
*/
static int
computeColumnNames(
  Tcl_Interp *interp, 
  sqlite3_stmt *pStmt,              /* SQL statement */
  Tcl_Obj ***papColName,            /* OUT: Array of column names */
  Tcl_Obj *pArray                   /* Name of array variable (may be null) */
){

  int nCol;


















  /* Compute column names */






  nCol = sqlite3_column_count(pStmt);
  if( papColName ){
    int i;
    Tcl_Obj **apColName = (Tcl_Obj**)Tcl_Alloc( sizeof(Tcl_Obj*)*nCol );
    for(i=0; i<nCol; i++){
      apColName[i] = dbTextToObj(sqlite3_column_name(pStmt,i));
      Tcl_IncrRefCount(apColName[i]);


    }

    /* If results are being stored in an array variable, then create
    ** the array(*) entry for that array
    */
    if( pArray ){

      Tcl_Obj *pColList = Tcl_NewObj();
      Tcl_Obj *pStar = Tcl_NewStringObj("*", -1);
      Tcl_IncrRefCount(pColList);

      for(i=0; i<nCol; i++){
        Tcl_ListObjAppendElement(interp, pColList, apColName[i]);
      }
      Tcl_IncrRefCount(pStar);
      Tcl_ObjSetVar2(interp, pArray, pStar, pColList,0);
      Tcl_DecrRefCount(pColList);















































































      Tcl_DecrRefCount(pStar);

    }






















































































    *papColName = apColName;







  }



























  return nCol;
}

/*
** The "sqlite" command below creates a new Tcl command for each
** connection it opens to an SQLite database.  This routine is invoked
** whenever one of those connection-specific commands is executed
** in Tcl.  For example, if you run Tcl code like this:
................................................................................
  ** Return the numeric error code that was returned by the most recent
  ** call to sqlite3_exec().
  */
  case DB_ERRORCODE: {
    Tcl_SetObjResult(interp, Tcl_NewIntObj(sqlite3_errcode(pDb->db)));
    break;
  }
   
  /*
  **    $db eval $sql ?array? ?{  ...code... }?
  **    $db onecolumn $sql































  **
  ** The SQL statement in $sql is evaluated.  For each row, the values are
  ** placed in elements of the array named "array" and ...code... is executed.
  ** If "array" and "code" are omitted, then no callback is every invoked.
  ** If "array" is an empty string, then the values are placed in variables
  ** that have the same name as the fields extracted by the query.
  **
  ** The onecolumn method is the equivalent of:
  **     lindex [$db eval $sql] 0
  */
  case DB_ONECOLUMN:
  case DB_EVAL:
  case DB_EXISTS: {
    char const *zSql;      /* Next SQL statement to execute */
    char const *zLeft;     /* What is left after first stmt in zSql */
    sqlite3_stmt *pStmt;   /* Compiled SQL statment */
    Tcl_Obj *pArray;       /* Name of array into which results are written */
    Tcl_Obj *pScript;      /* Script to run for each result set */
    Tcl_Obj **apParm;      /* Parameters that need a Tcl_DecrRefCount() */
    int nParm;             /* Number of entries used in apParm[] */
    Tcl_Obj *aParm[10];    /* Static space for apParm[] in the common case */
    Tcl_Obj *pRet;         /* Value to be returned */
    SqlPreparedStmt *pPreStmt;  /* Pointer to a prepared statement */
    int rc2;

    if( choice==DB_EVAL ){
      if( objc<3 || objc>5 ){
        Tcl_WrongNumArgs(interp, 2, objv, "SQL ?ARRAY-NAME? ?SCRIPT?");
        return TCL_ERROR;
      }
      pRet = Tcl_NewObj();
      Tcl_IncrRefCount(pRet);
    }else{
      if( objc!=3 ){
        Tcl_WrongNumArgs(interp, 2, objv, "SQL");
        return TCL_ERROR;
      }
      if( choice==DB_EXISTS ){
        pRet = Tcl_NewBooleanObj(0);
        Tcl_IncrRefCount(pRet);
      }else{
        pRet = 0;
      }
    }
    if( objc==3 ){
      pArray = pScript = 0;
    }else if( objc==4 ){
      pArray = 0;
      pScript = objv[3];
    }else{
      pArray = objv[3];
      if( Tcl_GetString(pArray)[0]==0 ) pArray = 0;
      pScript = objv[4];
    }



    Tcl_IncrRefCount(objv[2]);
    zSql = Tcl_GetStringFromObj(objv[2], 0);
    while( rc==TCL_OK && zSql[0] ){
      int i;                     /* Loop counter */
      int nVar;                  /* Number of bind parameters in the pStmt */
      int nCol = -1;             /* Number of columns in the result set */
      Tcl_Obj **apColName = 0;   /* Array of column names */
      int len;                   /* String length of zSql */
  
      /* Try to find a SQL statement that has already been compiled and
      ** which matches the next sequence of SQL.
      */
      pStmt = 0;
      while( isspace(zSql[0]) ){ zSql++; }
      len = strlen30(zSql);
      for(pPreStmt = pDb->stmtList; pPreStmt; pPreStmt=pPreStmt->pNext){
        int n = pPreStmt->nSql;
        if( len>=n 
            && memcmp(pPreStmt->zSql, zSql, n)==0
            && (zSql[n]==0 || zSql[n-1]==';')
        ){
          pStmt = pPreStmt->pStmt;
          zLeft = &zSql[pPreStmt->nSql];

          /* When a prepared statement is found, unlink it from the
          ** cache list.  It will later be added back to the beginning
          ** of the cache list in order to implement LRU replacement.
          */
          if( pPreStmt->pPrev ){
            pPreStmt->pPrev->pNext = pPreStmt->pNext;
          }else{
            pDb->stmtList = pPreStmt->pNext;
          }
          if( pPreStmt->pNext ){
            pPreStmt->pNext->pPrev = pPreStmt->pPrev;
          }else{
            pDb->stmtLast = pPreStmt->pPrev;
          }
          pDb->nStmt--;
          break;
        }
      }
  
      /* If no prepared statement was found.  Compile the SQL text
      */
      if( pStmt==0 ){
        if( SQLITE_OK!=sqlite3_prepare_v2(pDb->db, zSql, -1, &pStmt, &zLeft) ){
          Tcl_SetObjResult(interp, dbTextToObj(sqlite3_errmsg(pDb->db)));
          rc = TCL_ERROR;
          break;
        }
        if( pStmt==0 ){
          if( SQLITE_OK!=sqlite3_errcode(pDb->db) ){
            /* A compile-time error in the statement
            */
            Tcl_SetObjResult(interp, dbTextToObj(sqlite3_errmsg(pDb->db)));
            rc = TCL_ERROR;
            break;
          }else{
            /* The statement was a no-op.  Continue to the next statement
            ** in the SQL string.
            */
            zSql = zLeft;
            continue;
          }
        }
        assert( pPreStmt==0 );
      }

      /* Bind values to parameters that begin with $ or :
      */  
      nVar = sqlite3_bind_parameter_count(pStmt);
      nParm = 0;
      if( nVar>sizeof(aParm)/sizeof(aParm[0]) ){
        apParm = (Tcl_Obj**)Tcl_Alloc(nVar*sizeof(apParm[0]));
      }else{
        apParm = aParm;
      }
      for(i=1; i<=nVar; i++){
        const char *zVar = sqlite3_bind_parameter_name(pStmt, i);
        if( zVar!=0 && (zVar[0]=='$' || zVar[0]==':' || zVar[0]=='@') ){
          Tcl_Obj *pVar = Tcl_GetVar2Ex(interp, &zVar[1], 0, 0);
          if( pVar ){



            int n;
            u8 *data;
            char *zType = pVar->typePtr ? pVar->typePtr->name : "";
            char c = zType[0];
            if( zVar[0]=='@' ||
               (c=='b' && strcmp(zType,"bytearray")==0 && pVar->bytes==0) ){
              /* Load a BLOB type if the Tcl variable is a bytearray and
              ** it has no string representation or the host
              ** parameter name begins with "@". */
              data = Tcl_GetByteArrayFromObj(pVar, &n);
              sqlite3_bind_blob(pStmt, i, data, n, SQLITE_STATIC);
              Tcl_IncrRefCount(pVar);
              apParm[nParm++] = pVar;
            }else if( c=='b' && strcmp(zType,"boolean")==0 ){
              Tcl_GetIntFromObj(interp, pVar, &n);
              sqlite3_bind_int(pStmt, i, n);
            }else if( c=='d' && strcmp(zType,"double")==0 ){
              double r;
              Tcl_GetDoubleFromObj(interp, pVar, &r);
              sqlite3_bind_double(pStmt, i, r);
            }else if( (c=='w' && strcmp(zType,"wideInt")==0) ||
                  (c=='i' && strcmp(zType,"int")==0) ){
              Tcl_WideInt v;
              Tcl_GetWideIntFromObj(interp, pVar, &v);
              sqlite3_bind_int64(pStmt, i, v);
            }else{
              data = (unsigned char *)Tcl_GetStringFromObj(pVar, &n);
              sqlite3_bind_text(pStmt, i, (char *)data, n, SQLITE_STATIC);
              Tcl_IncrRefCount(pVar);
              apParm[nParm++] = pVar;
            }
          }else{
            sqlite3_bind_null( pStmt, i );
          }
        }
      }

      /* Execute the SQL
      */
      while( rc==TCL_OK && pStmt && SQLITE_ROW==sqlite3_step(pStmt) ){

	/* Compute column names. This must be done after the first successful
	** call to sqlite3_step(), in case the query is recompiled and the
        ** number or names of the returned columns changes. 
        */
        assert(!pArray||pScript);
        if (nCol < 0) {
          Tcl_Obj ***ap = (pScript?&apColName:0);
          nCol = computeColumnNames(interp, pStmt, ap, pArray);
        }


        for(i=0; i<nCol; i++){
          Tcl_Obj *pVal;
          
          /* Set pVal to contain the i'th column of this row. */
          switch( sqlite3_column_type(pStmt, i) ){
            case SQLITE_BLOB: {
              int bytes = sqlite3_column_bytes(pStmt, i);
              const char *zBlob = sqlite3_column_blob(pStmt, i);
              if( !zBlob ) bytes = 0;
              pVal = Tcl_NewByteArrayObj((u8*)zBlob, bytes);
              break;
            }
            case SQLITE_INTEGER: {
              sqlite_int64 v = sqlite3_column_int64(pStmt, i);
              if( v>=-2147483647 && v<=2147483647 ){
                pVal = Tcl_NewIntObj(v);
              }else{
                pVal = Tcl_NewWideIntObj(v);
              }
              break;
            }
            case SQLITE_FLOAT: {
              double r = sqlite3_column_double(pStmt, i);
              pVal = Tcl_NewDoubleObj(r);
              break;
            }
            case SQLITE_NULL: {
              pVal = dbTextToObj(pDb->zNull);
              break;
            }
            default: {
              pVal = dbTextToObj((char *)sqlite3_column_text(pStmt, i));
              break;
            }
          }
  
          if( pScript ){
            if( pArray==0 ){
              Tcl_ObjSetVar2(interp, apColName[i], 0, pVal, 0);
            }else{
              Tcl_ObjSetVar2(interp, pArray, apColName[i], pVal, 0);
            }
          }else if( choice==DB_ONECOLUMN ){
            assert( pRet==0 );
            if( pRet==0 ){
              pRet = pVal;
              Tcl_IncrRefCount(pRet);
            }
            rc = TCL_BREAK;
            i = nCol;
          }else if( choice==DB_EXISTS ){
            Tcl_DecrRefCount(pRet);
            pRet = Tcl_NewBooleanObj(1);
            Tcl_IncrRefCount(pRet);
            rc = TCL_BREAK;
            i = nCol;
          }else{
            Tcl_ListObjAppendElement(interp, pRet, pVal);
          }
        }
  
        if( pScript ){
          pDb->nStep = sqlite3_stmt_status(pStmt, 
                                  SQLITE_STMTSTATUS_FULLSCAN_STEP, 0);
          pDb->nSort = sqlite3_stmt_status(pStmt,
                                  SQLITE_STMTSTATUS_SORT, 0);
          rc = Tcl_EvalObjEx(interp, pScript, 0);
          if( rc==TCL_CONTINUE ){
            rc = TCL_OK;
          }
        }
      }

      if( rc==TCL_BREAK ){

        rc = TCL_OK;
      }

      /* Free the column name objects */
      if( pScript ){
        /* If the query returned no rows, but an array variable was 
        ** specified, call computeColumnNames() now to populate the 
        ** arrayname(*) variable.
        */
        if (pArray && nCol < 0) {
          Tcl_Obj ***ap = (pScript?&apColName:0);
          nCol = computeColumnNames(interp, pStmt, ap, pArray);
        }
        for(i=0; i<nCol; i++){
          Tcl_DecrRefCount(apColName[i]);
        }
        Tcl_Free((char*)apColName);
      }

      /* Free the bound string and blob parameters */
      for(i=0; i<nParm; i++){
        Tcl_DecrRefCount(apParm[i]);
      }
      if( apParm!=aParm ){
        Tcl_Free((char*)apParm);
      }

      /* Reset the statement.  If the result code is SQLITE_SCHEMA, then
      ** flush the statement cache and try the statement again.
      */
      rc2 = sqlite3_reset(pStmt);
      pDb->nStep = sqlite3_stmt_status(pStmt, 
                                  SQLITE_STMTSTATUS_FULLSCAN_STEP, 1);
      pDb->nSort = sqlite3_stmt_status(pStmt,
                                  SQLITE_STMTSTATUS_SORT, 1);
      if( SQLITE_OK!=rc2 ){
        /* If a run-time error occurs, report the error and stop reading
        ** the SQL
        */
        Tcl_SetObjResult(interp, dbTextToObj(sqlite3_errmsg(pDb->db)));
        sqlite3_finalize(pStmt);
        rc = TCL_ERROR;
        if( pPreStmt ) Tcl_Free((char*)pPreStmt);
        break;
      }else if( pDb->maxStmt<=0 ){
        /* If the cache is turned off, deallocated the statement */
        if( pPreStmt ) Tcl_Free((char*)pPreStmt);
        sqlite3_finalize(pStmt);
      }else{
        /* Everything worked and the cache is operational.
        ** Create a new SqlPreparedStmt structure if we need one.
        ** (If we already have one we can just reuse it.)
        */
        if( pPreStmt==0 ){
          len = zLeft - zSql;
          pPreStmt = (SqlPreparedStmt*)Tcl_Alloc( sizeof(*pPreStmt) );
          if( pPreStmt==0 ) return TCL_ERROR;
          pPreStmt->pStmt = pStmt;
          pPreStmt->nSql = len;
          pPreStmt->zSql = sqlite3_sql(pStmt);
          assert( strlen30(pPreStmt->zSql)==len );
          assert( 0==memcmp(pPreStmt->zSql, zSql, len) );




        }



        /* Add the prepared statement to the beginning of the cache list
        */
        pPreStmt->pNext = pDb->stmtList;
        pPreStmt->pPrev = 0;
        if( pDb->stmtList ){
         pDb->stmtList->pPrev = pPreStmt;
        }
        pDb->stmtList = pPreStmt;
        if( pDb->stmtLast==0 ){
          assert( pDb->nStmt==0 );
          pDb->stmtLast = pPreStmt;
        }else{
          assert( pDb->nStmt>0 );
        }
        pDb->nStmt++;
   
        /* If we have too many statement in cache, remove the surplus from the
        ** end of the cache list.
        */
        while( pDb->nStmt>pDb->maxStmt ){
          sqlite3_finalize(pDb->stmtLast->pStmt);
          pDb->stmtLast = pDb->stmtLast->pPrev;
          Tcl_Free((char*)pDb->stmtLast->pNext);
          pDb->stmtLast->pNext = 0;
          pDb->nStmt--;
        }
      }

      /* Proceed to the next statement */
      zSql = zLeft;
    }

    Tcl_DecrRefCount(objv[2]);

    if( pRet ){
      if( rc==TCL_OK ){
        Tcl_SetObjResult(interp, pRet);


      }
      Tcl_DecrRefCount(pRet);
    }else if( rc==TCL_OK ){
      Tcl_ResetResult(interp);



    }
    break;
  }

  /*
  **     $db function NAME [-argcount N] SCRIPT
  **
................................................................................
    rowid = sqlite3_last_insert_rowid(pDb->db);
    pResult = Tcl_GetObjResult(interp);
    Tcl_SetWideIntObj(pResult, rowid);
    break;
  }

  /*
  ** The DB_ONECOLUMN method is implemented together with DB_EVAL.
  */

  /*    $db progress ?N CALLBACK?
  ** 
  ** Invoke the given callback every N virtual machine opcodes while executing
  ** queries.
  */
................................................................................
  **
  ** This command was inspired by Dave Thomas's talk on Ruby at the
  ** 2005 O'Reilly Open Source Convention (OSCON).
  */
  case DB_TRANSACTION: {
    Tcl_Obj *pScript;
    const char *zBegin = "SAVEPOINT _tcl_transaction";
    const char *zEnd;
    if( objc!=3 && objc!=4 ){
      Tcl_WrongNumArgs(interp, 2, objv, "[TYPE] SCRIPT");
      return TCL_ERROR;
    }

    if( pDb->nTransaction ){
      zBegin = "SAVEPOINT _tcl_transaction";
    }else if( pDb->nTransaction==0 && objc==4 ){
      static const char *TTYPE_strs[] = {
        "deferred",   "exclusive",  "immediate", 0
      };
      enum TTYPE_enum {
        TTYPE_DEFERRED, TTYPE_EXCLUSIVE, TTYPE_IMMEDIATE
      };
      int ttype;
................................................................................
        case TTYPE_DEFERRED:    /* no-op */;                 break;
        case TTYPE_EXCLUSIVE:   zBegin = "BEGIN EXCLUSIVE";  break;
        case TTYPE_IMMEDIATE:   zBegin = "BEGIN IMMEDIATE";  break;
      }
    }
    pScript = objv[objc-1];


    pDb->disableAuth++;
    rc = sqlite3_exec(pDb->db, zBegin, 0, 0, 0);
    pDb->disableAuth--;
    if( rc!=SQLITE_OK ){
      Tcl_AppendResult(interp, sqlite3_errmsg(pDb->db), 0);
      return TCL_ERROR;
    }

    pDb->nTransaction++;
    rc = Tcl_EvalObjEx(interp, pScript, 0);
    pDb->nTransaction--;




    if( rc!=TCL_ERROR ){
      if( pDb->nTransaction ){
        zEnd = "RELEASE _tcl_transaction";
      }else{
        zEnd = "COMMIT";
      }
    }else{
      if( pDb->nTransaction ){
        zEnd = "ROLLBACK TO _tcl_transaction ; RELEASE _tcl_transaction";
      }else{
        zEnd = "ROLLBACK";

      }
    }

    pDb->disableAuth++;
    if( sqlite3_exec(pDb->db, zEnd, 0, 0, 0) ){
      /* This is a tricky scenario to handle. The most likely cause of an
      ** error is that the exec() above was an attempt to commit the 
      ** top-level transaction that returned SQLITE_BUSY. Or, less likely,
      ** that an IO-error has occured. In either case, throw a Tcl exception
      ** and try to rollback the transaction.
      **
      ** But it could also be that the user executed one or more BEGIN, 
      ** COMMIT, SAVEPOINT, RELEASE or ROLLBACK commands that are confusing
      ** this method's logic. Not clear how this would be best handled.
      */
      if( rc!=TCL_ERROR ){
        Tcl_AppendResult(interp, sqlite3_errmsg(pDb->db), 0);
        rc = TCL_ERROR;
      }
      sqlite3_exec(pDb->db, "ROLLBACK", 0, 0, 0);
    }
    pDb->disableAuth--;

    break;
  }

  /*
  **    $db unlock_notify ?script?
  */
  case DB_UNLOCK_NOTIFY: {
................................................................................
    Tcl_Free((char*)p);
    sqlite3_free(zErrMsg);
    return TCL_ERROR;
  }
  p->maxStmt = NUM_PREPARED_STMTS;
  p->interp = interp;
  zArg = Tcl_GetStringFromObj(objv[1], 0);



  Tcl_CreateObjCommand(interp, zArg, DbObjCmd, (char*)p, DbDeleteCmd);

  return TCL_OK;
}

/*
** Provide a dummy Tcl_InitStubs if we are using this as a static
** library.
*/

typedef struct SqlPreparedStmt SqlPreparedStmt;
struct SqlPreparedStmt {
  SqlPreparedStmt *pNext;  /* Next in linked list */
  SqlPreparedStmt *pPrev;  /* Previous on the list */
  sqlite3_stmt *pStmt;     /* The prepared statement */
  int nSql;                /* chars in zSql[] */
  const char *zSql;        /* Text of the SQL statement */
  int nParm;               /* Size of apParm array */
  Tcl_Obj **apParm;        /* Array of referenced object pointers */
};

typedef struct IncrblobChannel IncrblobChannel;

/*
** There is one instance of this structure for each SQLite database
** that has been opened by the SQLite TCL interface.
................................................................................

  if( rc && rc!=TCL_RETURN ){
    sqlite3_result_error(context, Tcl_GetStringResult(p->interp), -1); 
  }else{
    Tcl_Obj *pVar = Tcl_GetObjResult(p->interp);
    int n;
    u8 *data;
    const char *zType = (pVar->typePtr ? pVar->typePtr->name : "");
    char c = zType[0];
    if( c=='b' && strcmp(zType,"bytearray")==0 && pVar->bytes==0 ){
      /* Only return a BLOB type if the Tcl variable is a bytearray and
      ** has no string representation. */
      data = Tcl_GetByteArrayFromObj(pVar, &n);
      sqlite3_result_blob(context, data, n, SQLITE_TRANSIENT);
    }else if( c=='b' && strcmp(zType,"boolean")==0 ){
................................................................................
  }
  zLine = realloc( zLine, n+1 );
  return zLine;
}


/*
** This function is part of the implementation of the command:
**
**   $db transaction [-deferred|-immediate|-exclusive] SCRIPT
**

** It is invoked after evaluating the script SCRIPT to commit or rollback
** the transaction or savepoint opened by the [transaction] command.
*/
static int DbTransPostCmd(
  ClientData data[],                   /* data[0] is the Sqlite3Db* for $db */
  Tcl_Interp *interp,                  /* Tcl interpreter */
  int result                           /* Result of evaluating SCRIPT */
){
  static const char *azEnd[] = {
    "RELEASE _tcl_transaction",        /* rc==TCL_ERROR, nTransaction!=0 */
    "COMMIT",                          /* rc!=TCL_ERROR, nTransaction==0 */
    "ROLLBACK TO _tcl_transaction ; RELEASE _tcl_transaction",
    "ROLLBACK"                         /* rc==TCL_ERROR, nTransaction==0 */
  };
  SqliteDb *pDb = (SqliteDb*)data[0];
  int rc = result;
  const char *zEnd;

  pDb->nTransaction--;
  zEnd = azEnd[(rc==TCL_ERROR)*2 + (pDb->nTransaction==0)];

  pDb->disableAuth++;
  if( sqlite3_exec(pDb->db, zEnd, 0, 0, 0) ){
      /* This is a tricky scenario to handle. The most likely cause of an
      ** error is that the exec() above was an attempt to commit the 
      ** top-level transaction that returned SQLITE_BUSY. Or, less likely,
      ** that an IO-error has occured. In either case, throw a Tcl exception
      ** and try to rollback the transaction.
      **


      ** But it could also be that the user executed one or more BEGIN, 
      ** COMMIT, SAVEPOINT, RELEASE or ROLLBACK commands that are confusing
      ** this method's logic. Not clear how this would be best handled.
      */
    if( rc!=TCL_ERROR ){
      Tcl_AppendResult(interp, sqlite3_errmsg(pDb->db), 0);
      rc = TCL_ERROR;
    }
    sqlite3_exec(pDb->db, "ROLLBACK", 0, 0, 0);
  }
  pDb->disableAuth--;

  return rc;
}

/*
** Search the cache for a prepared-statement object that implements the
** first SQL statement in the buffer pointed to by parameter zIn. If
** no such prepared-statement can be found, allocate and prepare a new
** one. In either case, bind the current values of the relevant Tcl
** variables to any $var, :var or @var variables in the statement. Before
** returning, set *ppPreStmt to point to the prepared-statement object.
**
** Output parameter *pzOut is set to point to the next SQL statement in
** buffer zIn, or to the '\0' byte at the end of zIn if there is no
** next statement.
**
** If successful, TCL_OK is returned. Otherwise, TCL_ERROR is returned
** and an error message loaded into interpreter pDb->interp.
*/
static int dbPrepareAndBind(
  SqliteDb *pDb,                  /* Database object */
  char const *zIn,                /* SQL to compile */
  char const **pzOut,             /* OUT: Pointer to next SQL statement */
  SqlPreparedStmt **ppPreStmt     /* OUT: Object used to cache statement */
){
  const char *zSql = zIn;         /* Pointer to first SQL statement in zIn */
  sqlite3_stmt *pStmt;            /* Prepared statement object */
  SqlPreparedStmt *pPreStmt;      /* Pointer to cached statement */
  int nSql;                       /* Length of zSql in bytes */
  int nVar;                       /* Number of variables in statement */
  int iParm = 0;                  /* Next free entry in apParm */
  int i;
  Tcl_Interp *interp = pDb->interp;

  *ppPreStmt = 0;

  /* Trim spaces from the start of zSql and calculate the remaining length. */
  while( isspace(zSql[0]) ){ zSql++; }
  nSql = strlen30(zSql);

  for(pPreStmt = pDb->stmtList; pPreStmt; pPreStmt=pPreStmt->pNext){
    int n = pPreStmt->nSql;
    if( nSql>=n 
        && memcmp(pPreStmt->zSql, zSql, n)==0
        && (zSql[n]==0 || zSql[n-1]==';')
    ){
      pStmt = pPreStmt->pStmt;
      *pzOut = &zSql[pPreStmt->nSql];

      /* When a prepared statement is found, unlink it from the
      ** cache list.  It will later be added back to the beginning
      ** of the cache list in order to implement LRU replacement.
      */
      if( pPreStmt->pPrev ){
        pPreStmt->pPrev->pNext = pPreStmt->pNext;
      }else{
        pDb->stmtList = pPreStmt->pNext;
      }
      if( pPreStmt->pNext ){
        pPreStmt->pNext->pPrev = pPreStmt->pPrev;
      }else{
        pDb->stmtLast = pPreStmt->pPrev;
      }
      pDb->nStmt--;
      nVar = sqlite3_bind_parameter_count(pStmt);
      break;
    }
  }
  
  /* If no prepared statement was found. Compile the SQL text. Also allocate
  ** a new SqlPreparedStmt structure.  */
  if( pPreStmt==0 ){
    int nByte;

    if( SQLITE_OK!=sqlite3_prepare_v2(pDb->db, zSql, -1, &pStmt, pzOut) ){
      Tcl_SetObjResult(interp, dbTextToObj(sqlite3_errmsg(pDb->db)));
      return TCL_ERROR;
    }
    if( pStmt==0 ){
      if( SQLITE_OK!=sqlite3_errcode(pDb->db) ){
        /* A compile-time error in the statement. */
        Tcl_SetObjResult(interp, dbTextToObj(sqlite3_errmsg(pDb->db)));
        return TCL_ERROR;
      }else{
        /* The statement was a no-op.  Continue to the next statement
        ** in the SQL string.
        */
        return TCL_OK;
      }
    }

    assert( pPreStmt==0 );
    nVar = sqlite3_bind_parameter_count(pStmt);
    nByte = sizeof(SqlPreparedStmt) + nVar*sizeof(Tcl_Obj *);
    pPreStmt = (SqlPreparedStmt*)Tcl_Alloc(nByte);
    memset(pPreStmt, 0, nByte);

    pPreStmt->pStmt = pStmt;
    pPreStmt->nSql = (*pzOut - zSql);
    pPreStmt->zSql = sqlite3_sql(pStmt);
    pPreStmt->apParm = (Tcl_Obj **)&pPreStmt[1];
  }
  assert( pPreStmt );
  assert( strlen30(pPreStmt->zSql)==pPreStmt->nSql );
  assert( 0==memcmp(pPreStmt->zSql, zSql, pPreStmt->nSql) );

  /* Bind values to parameters that begin with $ or : */  
  for(i=1; i<=nVar; i++){
    const char *zVar = sqlite3_bind_parameter_name(pStmt, i);
    if( zVar!=0 && (zVar[0]=='$' || zVar[0]==':' || zVar[0]=='@') ){
      Tcl_Obj *pVar = Tcl_GetVar2Ex(interp, &zVar[1], 0, 0);
      if( pVar ){
        int n;
        u8 *data;
        const char *zType = (pVar->typePtr ? pVar->typePtr->name : "");
        char c = zType[0];
        if( zVar[0]=='@' ||
           (c=='b' && strcmp(zType,"bytearray")==0 && pVar->bytes==0) ){
          /* Load a BLOB type if the Tcl variable is a bytearray and
          ** it has no string representation or the host
          ** parameter name begins with "@". */
          data = Tcl_GetByteArrayFromObj(pVar, &n);
          sqlite3_bind_blob(pStmt, i, data, n, SQLITE_STATIC);
          Tcl_IncrRefCount(pVar);
          pPreStmt->apParm[iParm++] = pVar;
        }else if( c=='b' && strcmp(zType,"boolean")==0 ){
          Tcl_GetIntFromObj(interp, pVar, &n);
          sqlite3_bind_int(pStmt, i, n);
        }else if( c=='d' && strcmp(zType,"double")==0 ){
          double r;
          Tcl_GetDoubleFromObj(interp, pVar, &r);
          sqlite3_bind_double(pStmt, i, r);
        }else if( (c=='w' && strcmp(zType,"wideInt")==0) ||
              (c=='i' && strcmp(zType,"int")==0) ){
          Tcl_WideInt v;
          Tcl_GetWideIntFromObj(interp, pVar, &v);
          sqlite3_bind_int64(pStmt, i, v);
        }else{
          data = (unsigned char *)Tcl_GetStringFromObj(pVar, &n);
          sqlite3_bind_text(pStmt, i, (char *)data, n, SQLITE_STATIC);
          Tcl_IncrRefCount(pVar);
          pPreStmt->apParm[iParm++] = pVar;
        }
      }else{
        sqlite3_bind_null(pStmt, i);
      }
    }
  }
  pPreStmt->nParm = iParm;
  *ppPreStmt = pPreStmt;
  return TCL_OK;
}


/*
** Release a statement reference obtained by calling dbPrepareAndBind().
** There should be exactly one call to this function for each call to
** dbPrepareAndBind().
**
** If the discard parameter is non-zero, then the statement is deleted
** immediately. Otherwise it is added to the LRU list and may be returned
** by a subsequent call to dbPrepareAndBind().
*/
static void dbReleaseStmt(
  SqliteDb *pDb,                  /* Database handle */
  SqlPreparedStmt *pPreStmt,      /* Prepared statement handle to release */
  int discard                     /* True to delete (not cache) the pPreStmt */
){
  int i;

  /* Free the bound string and blob parameters */
  for(i=0; i<pPreStmt->nParm; i++){
    Tcl_DecrRefCount(pPreStmt->apParm[i]);
  }
  pPreStmt->nParm = 0;

  if( pDb->maxStmt<=0 || discard ){
    /* If the cache is turned off, deallocated the statement */
    sqlite3_finalize(pPreStmt->pStmt);
    Tcl_Free((char *)pPreStmt);
  }else{
    /* Add the prepared statement to the beginning of the cache list. */
    pPreStmt->pNext = pDb->stmtList;
    pPreStmt->pPrev = 0;
    if( pDb->stmtList ){
     pDb->stmtList->pPrev = pPreStmt;
    }
    pDb->stmtList = pPreStmt;
    if( pDb->stmtLast==0 ){
      assert( pDb->nStmt==0 );
      pDb->stmtLast = pPreStmt;
    }else{
      assert( pDb->nStmt>0 );
    }
    pDb->nStmt++;
   
    /* If we have too many statement in cache, remove the surplus from 
    ** the end of the cache list.  */
    while( pDb->nStmt>pDb->maxStmt ){
      sqlite3_finalize(pDb->stmtLast->pStmt);
      pDb->stmtLast = pDb->stmtLast->pPrev;
      Tcl_Free((char*)pDb->stmtLast->pNext);
      pDb->stmtLast->pNext = 0;
      pDb->nStmt--;
    }
  }
}

/*
** Structure used with dbEvalXXX() functions:
**
**   dbEvalInit()
**   dbEvalStep()
**   dbEvalFinalize()
**   dbEvalRowInfo()
**   dbEvalColumnValue()
*/
typedef struct DbEvalContext DbEvalContext;
struct DbEvalContext {
  SqliteDb *pDb;                  /* Database handle */
  Tcl_Obj *pSql;                  /* Object holding string zSql */
  const char *zSql;               /* Remaining SQL to execute */
  SqlPreparedStmt *pPreStmt;      /* Current statement */
  int nCol;                       /* Number of columns returned by pStmt */
  Tcl_Obj *pArray;                /* Name of array variable */
  Tcl_Obj **apColName;            /* Array of column names */
};

/*
** Release any cache of column names currently held as part of
** the DbEvalContext structure passed as the first argument.
*/
static void dbReleaseColumnNames(DbEvalContext *p){
  if( p->apColName ){
    int i;
    for(i=0; i<p->nCol; i++){
      Tcl_DecrRefCount(p->apColName[i]);
    }
    Tcl_Free((char *)p->apColName);
    p->apColName = 0;
  }
  p->nCol = 0;
}

/*
** Initialize a DbEvalContext structure.
**
** If pArray is not NULL, then it contains the name of a Tcl array
** variable. The "*" member of this array is set to a list containing
** the names of the columns returned by the statement as part of each
** call to dbEvalStep(), in order from left to right. e.g. if the names 
** of the returned columns are a, b and c, it does the equivalent of the 
** tcl command:
**
**     set ${pArray}(*) {a b c}
*/
static void dbEvalInit(
  DbEvalContext *p,               /* Pointer to structure to initialize */
  SqliteDb *pDb,                  /* Database handle */
  Tcl_Obj *pSql,                  /* Object containing SQL script */

  Tcl_Obj *pArray                 /* Name of Tcl array to set (*) element of */
){
  memset(p, 0, sizeof(DbEvalContext));
  p->pDb = pDb;
  p->zSql = Tcl_GetString(pSql);
  p->pSql = pSql;
  Tcl_IncrRefCount(pSql);
  if( pArray ){
    p->pArray = pArray;
    Tcl_IncrRefCount(pArray);
  }
}

/*
** Obtain information about the row that the DbEvalContext passed as the
** first argument currently points to.
*/
static void dbEvalRowInfo(
  DbEvalContext *p,               /* Evaluation context */
  int *pnCol,                     /* OUT: Number of column names */
  Tcl_Obj ***papColName           /* OUT: Array of column names */
){
  /* Compute column names */
  if( 0==p->apColName ){
    sqlite3_stmt *pStmt = p->pPreStmt->pStmt;
    int i;                        /* Iterator variable */
    int nCol;                     /* Number of columns returned by pStmt */
    Tcl_Obj **apColName = 0;      /* Array of column names */

    p->nCol = nCol = sqlite3_column_count(pStmt);
    if( nCol>0 && (papColName || p->pArray) ){

      apColName = (Tcl_Obj**)Tcl_Alloc( sizeof(Tcl_Obj*)*nCol );
      for(i=0; i<nCol; i++){
        apColName[i] = dbTextToObj(sqlite3_column_name(pStmt,i));
        Tcl_IncrRefCount(apColName[i]);
      }
      p->apColName = apColName;
    }

    /* If results are being stored in an array variable, then create
    ** the array(*) entry for that array
    */
    if( p->pArray ){
      Tcl_Interp *interp = p->pDb->interp;
      Tcl_Obj *pColList = Tcl_NewObj();
      Tcl_Obj *pStar = Tcl_NewStringObj("*", -1);


      for(i=0; i<nCol; i++){
        Tcl_ListObjAppendElement(interp, pColList, apColName[i]);
      }
      Tcl_IncrRefCount(pStar);
      Tcl_ObjSetVar2(interp, p->pArray, pStar, pColList, 0);
      Tcl_DecrRefCount(pStar);
    }
  }

  if( papColName ){
    *papColName = p->apColName;
  }
  if( pnCol ){
    *pnCol = p->nCol;
  }
}

/*
** Return one of TCL_OK, TCL_BREAK or TCL_ERROR. If TCL_ERROR is
** returned, then an error message is stored in the interpreter before
** returning.
**
** A return value of TCL_OK means there is a row of data available. The
** data may be accessed using dbEvalRowInfo() and dbEvalColumnValue(). This
** is analogous to a return of SQLITE_ROW from sqlite3_step(). If TCL_BREAK
** is returned, then the SQL script has finished executing and there are
** no further rows available. This is similar to SQLITE_DONE.
*/
static int dbEvalStep(DbEvalContext *p){
  while( p->zSql[0] || p->pPreStmt ){
    int rc;
    if( p->pPreStmt==0 ){
      rc = dbPrepareAndBind(p->pDb, p->zSql, &p->zSql, &p->pPreStmt);
      if( rc!=TCL_OK ) return rc;
    }else{
      int rcs;
      SqliteDb *pDb = p->pDb;
      SqlPreparedStmt *pPreStmt = p->pPreStmt;
      sqlite3_stmt *pStmt = pPreStmt->pStmt;

      rcs = sqlite3_step(pStmt);
      if( rcs==SQLITE_ROW ){
        return TCL_OK;
      }
      if( p->pArray ){
        dbEvalRowInfo(p, 0, 0);
      }
      rcs = sqlite3_reset(pStmt);

      pDb->nStep = sqlite3_stmt_status(pStmt,SQLITE_STMTSTATUS_FULLSCAN_STEP,1);
      pDb->nSort = sqlite3_stmt_status(pStmt,SQLITE_STMTSTATUS_SORT,1);
      dbReleaseColumnNames(p);
      p->pPreStmt = 0;

      if( rcs!=SQLITE_OK ){
        /* If a run-time error occurs, report the error and stop reading
        ** the SQL.  */
        Tcl_SetObjResult(pDb->interp, dbTextToObj(sqlite3_errmsg(pDb->db)));
        dbReleaseStmt(pDb, pPreStmt, 1);
        return TCL_ERROR;
      }else{
        dbReleaseStmt(pDb, pPreStmt, 0);
      }
    }
  }

  /* Finished */
  return TCL_BREAK;
}

/*
** Free all resources currently held by the DbEvalContext structure passed
** as the first argument. There should be exactly one call to this function
** for each call to dbEvalInit().
*/
static void dbEvalFinalize(DbEvalContext *p){
  if( p->pPreStmt ){
    sqlite3_reset(p->pPreStmt->pStmt);
    dbReleaseStmt(p->pDb, p->pPreStmt, 0);
    p->pPreStmt = 0;
  }
  if( p->pArray ){
    Tcl_DecrRefCount(p->pArray);
    p->pArray = 0;
  }
  Tcl_DecrRefCount(p->pSql);
  dbReleaseColumnNames(p);
}

/*
** Return a pointer to a Tcl_Obj structure with ref-count 0 that contains
** the value for the iCol'th column of the row currently pointed to by
** the DbEvalContext structure passed as the first argument.
*/
static Tcl_Obj *dbEvalColumnValue(DbEvalContext *p, int iCol){
  sqlite3_stmt *pStmt = p->pPreStmt->pStmt;
  switch( sqlite3_column_type(pStmt, iCol) ){
    case SQLITE_BLOB: {
      int bytes = sqlite3_column_bytes(pStmt, iCol);
      const char *zBlob = sqlite3_column_blob(pStmt, iCol);
      if( !zBlob ) bytes = 0;
      return Tcl_NewByteArrayObj((u8*)zBlob, bytes);
    }
    case SQLITE_INTEGER: {
      sqlite_int64 v = sqlite3_column_int64(pStmt, iCol);
      if( v>=-2147483647 && v<=2147483647 ){
        return Tcl_NewIntObj(v);
      }else{
        return Tcl_NewWideIntObj(v);
      }
    }
    case SQLITE_FLOAT: {
      return Tcl_NewDoubleObj(sqlite3_column_double(pStmt, iCol));
    }
    case SQLITE_NULL: {
      return dbTextToObj(p->pDb->zNull);
    }
  }

  return dbTextToObj((char *)sqlite3_column_text(pStmt, iCol));
}

/*
** If using Tcl version 8.6 or greater, use the NR functions to avoid
** recursive evalution of scripts by the [db eval] and [db trans]
** commands. Even if the headers used while compiling the extension
** are 8.6 or newer, the code still tests the Tcl version at runtime.
** This allows stubs-enabled builds to be used with older Tcl libraries.
*/
#if TCL_MAJOR_VERSION>8 || (TCL_MAJOR_VERSION==8 && TCL_MINOR_VERSION>=6)
static int DbUseNre(void){
  int major, minor;
  Tcl_GetVersion(&major, &minor, 0, 0);
  return( (major==8 && minor>=6) || major>8 );
}
#else
/* 
** Compiling using headers earlier than 8.6. In this case NR cannot be
** used, so DbUseNre() to always return zero. Add #defines for the other
** Tcl_NRxxx() functions to prevent them from causing compilation errors,
** even though the only invocations of them are within conditional blocks 
** of the form:
**
**   if( DbUseNre() ) { ... }
*/
# define DbUseNre() 0
# define Tcl_NRAddCallback(a,b,c,d,e,f) 0
# define Tcl_NREvalObj(a,b,c) 0
# define Tcl_NRCreateCommand(a,b,c,d,e,f) 0
#endif

/*
** This function is part of the implementation of the command:
**
**   $db eval SQL ?ARRAYNAME? SCRIPT
*/
static int DbEvalNextCmd(
  ClientData data[],                   /* data[0] is the (DbEvalContext*) */
  Tcl_Interp *interp,                  /* Tcl interpreter */
  int result                           /* Result so far */
){
  int rc = result;                     /* Return code */

  /* The first element of the data[] array is a pointer to a DbEvalContext
  ** structure allocated using Tcl_Alloc(). The second element of data[]
  ** is a pointer to a Tcl_Obj containing the script to run for each row
  ** returned by the queries encapsulated in data[0]. */
  DbEvalContext *p = (DbEvalContext *)data[0];
  Tcl_Obj *pScript = (Tcl_Obj *)data[1];
  Tcl_Obj *pArray = p->pArray;

  while( (rc==TCL_OK || rc==TCL_CONTINUE) && TCL_OK==(rc = dbEvalStep(p)) ){
    int i;
    int nCol;
    Tcl_Obj **apColName;
    dbEvalRowInfo(p, &nCol, &apColName);
    for(i=0; i<nCol; i++){
      Tcl_Obj *pVal = dbEvalColumnValue(p, i);
      if( pArray==0 ){
        Tcl_ObjSetVar2(interp, apColName[i], 0, pVal, 0);
      }else{
        Tcl_ObjSetVar2(interp, pArray, apColName[i], pVal, 0);
      }
    }

    /* The required interpreter variables are now populated with the data 
    ** from the current row. If using NRE, schedule callbacks to evaluate
    ** script pScript, then to invoke this function again to fetch the next
    ** row (or clean up if there is no next row or the script throws an
    ** exception). After scheduling the callbacks, return control to the 
    ** caller.
    **
    ** If not using NRE, evaluate pScript directly and continue with the
    ** next iteration of this while(...) loop.  */
    if( DbUseNre() ){
      Tcl_NRAddCallback(interp, DbEvalNextCmd, (void*)p, (void*)pScript, 0, 0);
      return Tcl_NREvalObj(interp, pScript, 0);
    }else{
      rc = Tcl_EvalObjEx(interp, pScript, 0);
    }
  }

  Tcl_DecrRefCount(pScript);
  dbEvalFinalize(p);
  Tcl_Free((char *)p);

  if( rc==TCL_OK || rc==TCL_BREAK ){
    Tcl_ResetResult(interp);
    rc = TCL_OK;
  }
  return rc;
}

/*
** The "sqlite" command below creates a new Tcl command for each
** connection it opens to an SQLite database.  This routine is invoked
** whenever one of those connection-specific commands is executed
** in Tcl.  For example, if you run Tcl code like this:
................................................................................
  ** Return the numeric error code that was returned by the most recent
  ** call to sqlite3_exec().
  */
  case DB_ERRORCODE: {
    Tcl_SetObjResult(interp, Tcl_NewIntObj(sqlite3_errcode(pDb->db)));
    break;
  }

  /*
  **    $db exists $sql
  **    $db onecolumn $sql
  **
  ** The onecolumn method is the equivalent of:
  **     lindex [$db eval $sql] 0
  */
  case DB_EXISTS: 
  case DB_ONECOLUMN: {
    DbEvalContext sEval;
    if( objc!=3 ){
      Tcl_WrongNumArgs(interp, 2, objv, "SQL");
      return TCL_ERROR;
    }

    dbEvalInit(&sEval, pDb, objv[2], 0);
    rc = dbEvalStep(&sEval);
    if( choice==DB_ONECOLUMN ){
      if( rc==TCL_OK ){
        Tcl_SetObjResult(interp, dbEvalColumnValue(&sEval, 0));
      }
    }else if( rc==TCL_BREAK || rc==TCL_OK ){
      Tcl_SetObjResult(interp, Tcl_NewBooleanObj(rc==TCL_OK));
    }
    dbEvalFinalize(&sEval);

    if( rc==TCL_BREAK ){
      rc = TCL_OK;
    }
    break;
  }
   
  /*
  **    $db eval $sql ?array? ?{  ...code... }?
  **
  ** The SQL statement in $sql is evaluated.  For each row, the values are
  ** placed in elements of the array named "array" and ...code... is executed.
  ** If "array" and "code" are omitted, then no callback is every invoked.
  ** If "array" is an empty string, then the values are placed in variables
  ** that have the same name as the fields extracted by the query.



  */

  case DB_EVAL: {














    if( objc<3 || objc>5 ){
      Tcl_WrongNumArgs(interp, 2, objv, "SQL ?ARRAY-NAME? ?SCRIPT?");
      return TCL_ERROR;
    }














    if( objc==3 ){










      DbEvalContext sEval;
      Tcl_Obj *pRet = Tcl_NewObj();
      Tcl_IncrRefCount(pRet);


















































































      dbEvalInit(&sEval, pDb, objv[2], 0);
      while( TCL_OK==(rc = dbEvalStep(&sEval)) ){
        int i;
        int nCol;


















































        dbEvalRowInfo(&sEval, &nCol, 0);
        for(i=0; i<nCol; i++){
























































          Tcl_ListObjAppendElement(interp, pRet, dbEvalColumnValue(&sEval, i));
        }
      }












      dbEvalFinalize(&sEval);
      if( rc==TCL_BREAK ){
        Tcl_SetObjResult(interp, pRet);
        rc = TCL_OK;
      }



















      Tcl_DecrRefCount(pRet);


























    }else{













      ClientData cd[2];
      DbEvalContext *p;
      Tcl_Obj *pArray = 0;
      Tcl_Obj *pScript;

      if( objc==5 && *(char *)Tcl_GetString(objv[3]) ){
        pArray = objv[3];
      }































      pScript = objv[objc-1];
      Tcl_IncrRefCount(pScript);
      



      p = (DbEvalContext *)Tcl_Alloc(sizeof(DbEvalContext));
      dbEvalInit(p, pDb, objv[2], pArray);




      cd[0] = (void *)p;
      cd[1] = (void *)pScript;
      rc = DbEvalNextCmd(cd, interp, TCL_OK);
    }
    break;
  }

  /*
  **     $db function NAME [-argcount N] SCRIPT
  **
................................................................................
    rowid = sqlite3_last_insert_rowid(pDb->db);
    pResult = Tcl_GetObjResult(interp);
    Tcl_SetWideIntObj(pResult, rowid);
    break;
  }

  /*
  ** The DB_ONECOLUMN method is implemented together with DB_EXISTS.
  */

  /*    $db progress ?N CALLBACK?
  ** 
  ** Invoke the given callback every N virtual machine opcodes while executing
  ** queries.
  */
................................................................................
  **
  ** This command was inspired by Dave Thomas's talk on Ruby at the
  ** 2005 O'Reilly Open Source Convention (OSCON).
  */
  case DB_TRANSACTION: {
    Tcl_Obj *pScript;
    const char *zBegin = "SAVEPOINT _tcl_transaction";

    if( objc!=3 && objc!=4 ){
      Tcl_WrongNumArgs(interp, 2, objv, "[TYPE] SCRIPT");
      return TCL_ERROR;
    }



    if( pDb->nTransaction==0 && objc==4 ){
      static const char *TTYPE_strs[] = {
        "deferred",   "exclusive",  "immediate", 0
      };
      enum TTYPE_enum {
        TTYPE_DEFERRED, TTYPE_EXCLUSIVE, TTYPE_IMMEDIATE
      };
      int ttype;
................................................................................
        case TTYPE_DEFERRED:    /* no-op */;                 break;
        case TTYPE_EXCLUSIVE:   zBegin = "BEGIN EXCLUSIVE";  break;
        case TTYPE_IMMEDIATE:   zBegin = "BEGIN IMMEDIATE";  break;
      }
    }
    pScript = objv[objc-1];

    /* Run the SQLite BEGIN command to open a transaction or savepoint. */
    pDb->disableAuth++;
    rc = sqlite3_exec(pDb->db, zBegin, 0, 0, 0);
    pDb->disableAuth--;
    if( rc!=SQLITE_OK ){
      Tcl_AppendResult(interp, sqlite3_errmsg(pDb->db), 0);
      return TCL_ERROR;
    }

    pDb->nTransaction++;



    /* If using NRE, schedule a callback to invoke the script pScript, then
    ** a second callback to commit (or rollback) the transaction or savepoint
    ** opened above. If not using NRE, evaluate the script directly, then
    ** call function DbTransPostCmd() to commit (or rollback) the transaction 
    ** or savepoint.  */
    if( DbUseNre() ){
      Tcl_NRAddCallback(interp, DbTransPostCmd, cd, 0, 0, 0);
      Tcl_NREvalObj(interp, pScript, 0);

    }else{




      rc = DbTransPostCmd(&cd, interp, Tcl_EvalObjEx(interp, pScript, 0));
    }






















    break;
  }

  /*
  **    $db unlock_notify ?script?
  */
  case DB_UNLOCK_NOTIFY: {
................................................................................
    Tcl_Free((char*)p);
    sqlite3_free(zErrMsg);
    return TCL_ERROR;
  }
  p->maxStmt = NUM_PREPARED_STMTS;
  p->interp = interp;
  zArg = Tcl_GetStringFromObj(objv[1], 0);
  if( DbUseNre() ){
    Tcl_NRCreateCommand(interp, zArg, 0, DbObjCmd, (char*)p, DbDeleteCmd);
  }else{
    Tcl_CreateObjCommand(interp, zArg, DbObjCmd, (char*)p, DbDeleteCmd);
  }
  return TCL_OK;
}

/*
** Provide a dummy Tcl_InitStubs if we are using this as a static
** library.
*/