SQLite

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 */
  int evalFlags;                  /* Flags used */
  Tcl_Obj *pArray;                /* Name of array variable */
  Tcl_Obj **apColName;            /* Array of column names */
};

#define SQLITE_EVAL_WITHOUTNULLS  0x00001  /* Unset array(*) for NULL */

/*
** 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 ){

**
**     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 */
  int evalFlags                   /* Flags controlling evaluation */
){
  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);
  }
  p->evalFlags = evalFlags;
}

/*
** Obtain information about the row that the DbEvalContext passed as the
** first argument currently points to.
*/
static void dbEvalRowInfo(

  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++){

      if( pArray==0 ){
        Tcl_ObjSetVar2(interp, apColName[i], 0, dbEvalColumnValue(p,i), 0);
      }else if( (p->evalFlags & SQLITE_EVAL_WITHOUTNULLS)!=0
             && sqlite3_column_type(p->pPreStmt->pStmt, i)==SQLITE_NULL 
      ){
        Tcl_UnsetVar2(interp, Tcl_GetString(pArray), 
                      Tcl_GetString(apColName[i]), 0);
      }else{
        Tcl_ObjSetVar2(interp, pArray, apColName[i], dbEvalColumnValue(p,i), 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

    Tcl_Obj *pResult = 0;
    DbEvalContext sEval;
    if( objc!=3 ){
      Tcl_WrongNumArgs(interp, 2, objv, "SQL");
      return TCL_ERROR;
    }

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

    if( rc==TCL_BREAK ){
      rc = TCL_OK;
    }
    break;
  }

  /*
  **    $db eval ?options? $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: {
    int evalFlags = 0;
    const char *zOpt;
    while( objc>3 && (zOpt = Tcl_GetString(objv[2]))!=0 && zOpt[0]=='-' ){
      if( strcmp(zOpt, "-withoutnulls")==0 ){
        evalFlags |= SQLITE_EVAL_WITHOUTNULLS;
      }
      else{
        Tcl_AppendResult(interp, "unknown option: \"", zOpt, "\"", (void*)0);
        return TCL_ERROR;
      }
      objc--;
      objv++;
    }
    if( objc<3 || objc>5 ){
      Tcl_WrongNumArgs(interp, 2, objv, 
          "?OPTIONS? 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, 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 cd2[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, evalFlags);

      cd2[0] = (void *)p;
      cd2[1] = (void *)pScript;
      rc = DbEvalNextCmd(cd2, interp, TCL_OK);
    }
    break;
  }

    set v [catch {db complete} msg]
    lappend v $msg
  } {1 {wrong # args: should be "db complete SQL"}}
}
do_test tcl-1.14 {
  set v [catch {db eval} msg]
  lappend v $msg
} {1 {wrong # args: should be "db eval ?OPTIONS? SQL ?ARRAY-NAME? ?SCRIPT?"}}
do_test tcl-1.15 {
  set v [catch {db function} msg]
  lappend v $msg
} {1 {wrong # args: should be "db function NAME ?SWITCHES? SCRIPT"}}
do_test tcl-1.16 {
  set v [catch {db last_insert_rowid xyz} msg]
  lappend v $msg

  db exists {SELECT a FROM t1 WHERE a>2}
} {1}
do_test tcl-15.5 {
  db exists {SELECT a FROM t1 WHERE a>3}
} {0}


# 2017-06-26: The --withoutnulls flag to "db eval".
#
# In the "db eval --withoutnulls SQL ARRAY" form, NULL results cause the
# corresponding array entry to be unset.  The default behavior (without
# the -withoutnulls flags) is for the corresponding array value to get
# the [db nullvalue] string.
#
catch {db close}
forcedelete test.db
sqlite3 db test.db
do_execsql_test tcl-16.100 {
  CREATE TABLE t1(a,b);
  INSERT INTO t1 VALUES(1,2),(2,NULL),(3,'xyz');
}
do_test tcl-16.101 {
  set res {}
  unset -nocomplain x
  db eval {SELECT * FROM t1} x {
    lappend res $x(a) [array names x]
  }
  set res
} {1 {a b *} 2 {a b *} 3 {a b *}}
do_test tcl-16.102 {
  set res [catch {
    db eval -unknown {SELECT * FROM t1} x {
      lappend res $x(a) [array names x]
    }
  } rc]
  lappend res $rc
} {1 {unknown option: "-unknown"}}
do_test tcl-16.103 {
  set res {}
  unset -nocomplain x
  db eval -withoutnulls {SELECT * FROM t1} x {
    lappend res $x(a) [array names x]
  }
  set res
} {1 {a b *} 2 {a *} 3 {a b *}}





finish_test