SQLite

    ** refer to this table (i.e. constraints attached to other tables) 
    ** are not violated by deleting this row.  */
    sqlite3FkCheck(pParse, pTab, iOld, 0);
  }

  /* Delete the index and table entries. Skip this step if pTab is really
  ** a view (in which case the only effect of the DELETE statement is to
  ** fire the INSTEAD OF triggers).  
  **
  ** If variable 'count' is non-zero, then this OP_Delete instruction should
  ** invoke the update-hook. The pre-update-hook, on the other hand should
  ** be invoked unless table pTab is a system table. The difference is that
  ** the update-hook is not invoked for rows removed by REPLACE, but the 
  ** pre-update-hook is.
  */ 
  if( pTab->pSelect==0 ){
    sqlite3GenerateRowIndexDelete(pParse, pTab, iCur, 0);
    sqlite3VdbeAddOp2(v, OP_Delete, iCur, (count?OPFLAG_NCHANGE:0));

    sqlite3VdbeChangeP4(v, -1, pTab->zName, P4_STATIC);

  }

  /* Do any ON CASCADE, SET NULL or SET DEFAULT operations required to
  ** handle rows (possibly in other tables) that refer via a foreign key
  ** to the row just deleted. */ 
  sqlite3FkActions(pParse, pTab, 0, iOld);

          pTrigger = sqlite3TriggersExist(pParse, pTab, TK_DELETE, 0, 0);
        }
        if( pTrigger || sqlite3FkRequired(pParse, pTab, 0, 0) ){
          sqlite3MultiWrite(pParse);
          sqlite3GenerateRowDelete(
              pParse, pTab, baseCur, regRowid, 0, pTrigger, OE_Replace
          );
        }else{
          /* This OP_Delete opcode fires the pre-update-hook only. It does
          ** not modify the b-tree. It is more efficient to let the coming
          ** OP_Insert replace the existing entry than it is to delete the
          ** existing entry and then insert a new one. */
          sqlite3VdbeAddOp2(v, OP_Delete, baseCur, OPFLAG_ISNOOP);
          sqlite3VdbeChangeP4(v, -1, pTab->zName, P4_STATIC);
          if( pTab->pIndex ){
            sqlite3MultiWrite(pParse);
            sqlite3GenerateRowIndexDelete(pParse, pTab, baseCur, 0);
          }
        }
        seenReplace = 1;
        break;
      }
      case OE_Ignore: {
        assert( seenReplace==0 );
        sqlite3VdbeAddOp2(v, OP_Goto, 0, ignoreDest);

  sqlite3_mutex_enter(db->mutex);
  pRet = db->pRollbackArg;
  db->xRollbackCallback = xCallback;
  db->pRollbackArg = pArg;
  sqlite3_mutex_leave(db->mutex);
  return pRet;
}

/*
** Register a callback to be invoked each time a row is updated,
** inserted or deleted using this database connection.
*/
void *sqlite3_preupdate_hook(
  sqlite3 *db,              /* Attach the hook to this database */
  void(*xCallback)(         /* Callback function */
    void*,sqlite3*,int,char const*,char const*,sqlite3_int64,sqlite3_int64),
  void *pArg                /* First callback argument */
){
  void *pRet;
  sqlite3_mutex_enter(db->mutex);
  pRet = db->pPreUpdateArg;
  db->xPreUpdateCallback = xCallback;
  db->pPreUpdateArg = pArg;
  sqlite3_mutex_leave(db->mutex);
  return pRet;
}

#ifndef SQLITE_OMIT_WAL
/*
** The sqlite3_wal_hook() callback registered by sqlite3_wal_autocheckpoint().
** Invoke sqlite3_wal_checkpoint if the number of frames in the log file
** is greater than sqlite3.pWalArg cast to an integer (the value configured by
** wal_autocheckpoint()).

** documentation for additional information about the meaning and use of
** each of these values.
*/
#define SQLITE_CHECKPOINT_PASSIVE 0
#define SQLITE_CHECKPOINT_FULL    1
#define SQLITE_CHECKPOINT_RESTART 2

void *sqlite3_preupdate_hook(
  sqlite3 *db,
  void(*xPreUpdate)(
    void *pCtx,                   /* Copy of third arg to preupdate_hook() */
    sqlite3 *db,                  /* Database handle */
    int op,                       /* SQLITE_UPDATE, DELETE or INSERT */
    char const *zDb,              /* Database name */
    char const *zName,            /* Table name */
    sqlite3_int64 iKey1,          /* Rowid of row about to be deleted/updated */
    sqlite3_int64 iKey2           /* New rowid value (for a rowid UPDATE) */
  ),
  void*
);

/*
** The following APIs may only be used from within a pre-update callback. More
** specifically, the preupdate_old() API may only be used from within an
** SQLITE_UPDATE or SQLITE_DELETE pre-update callback. The preupdate_modified()
** API may only be used from within an SQLITE_UPDATE pre-update callback.
*/
int sqlite3_preupdate_old(sqlite3 *, int, sqlite3_value **);
int sqlite3_preupdate_modified(sqlite3 *, int, int *);
int sqlite3_preupdate_count(sqlite3 *);


/*
** Undo the hack that converts floating point types to integer for
** builds on processors without floating point support.
*/
#ifdef SQLITE_OMIT_FLOATING_POINT
# undef double

typedef struct KeyClass KeyClass;
typedef struct KeyInfo KeyInfo;
typedef struct Lookaside Lookaside;
typedef struct LookasideSlot LookasideSlot;
typedef struct Module Module;
typedef struct NameContext NameContext;
typedef struct Parse Parse;
typedef struct PreUpdate PreUpdate;
typedef struct RowSet RowSet;
typedef struct Savepoint Savepoint;
typedef struct Select Select;
typedef struct SrcList SrcList;
typedef struct StrAccum StrAccum;
typedef struct Table Table;
typedef struct TableLock TableLock;

  void *pProfileArg;                        /* Argument to profile function */
  void *pCommitArg;                 /* Argument to xCommitCallback() */   
  int (*xCommitCallback)(void*);    /* Invoked at every commit. */
  void *pRollbackArg;               /* Argument to xRollbackCallback() */   
  void (*xRollbackCallback)(void*); /* Invoked at every commit. */
  void *pUpdateArg;
  void (*xUpdateCallback)(void*,int, const char*,const char*,sqlite_int64);
  void *pPreUpdateArg;          /* First argument to xPreUpdateCallback */
  void (*xPreUpdateCallback)(   /* Registered using sqlite3_preupdate_hook() */
    void*,sqlite3*,int,char const*,char const*,sqlite3_int64,sqlite3_int64
  );
  PreUpdate *pPreUpdate;        /* Context for active pre-update callback */
#ifndef SQLITE_OMIT_WAL
  int (*xWalCallback)(void *, sqlite3 *, const char *, int);
  void *pWalArg;
#endif
  void(*xCollNeeded)(void*,sqlite3*,int eTextRep,const char*);
  void(*xCollNeeded16)(void*,sqlite3*,int eTextRep,const void*);
  void *pCollNeededArg;

*/
#define OPFLAG_NCHANGE       0x01    /* Set to update db->nChange */
#define OPFLAG_LASTROWID     0x02    /* Set to update db->lastRowid */
#define OPFLAG_ISUPDATE      0x04    /* This OP_Insert is an sql UPDATE */
#define OPFLAG_APPEND        0x08    /* This is likely to be an append */
#define OPFLAG_USESEEKRESULT 0x10    /* Try to avoid a seek in BtreeInsert() */
#define OPFLAG_CLEARCACHE    0x20    /* Clear pseudo-table cache in OP_Column */
#define OPFLAG_ISNOOP        0x40    /* OP_Delete does pre-update-hook only */

/*
 * Each trigger present in the database schema is stored as an instance of
 * struct Trigger. 
 *
 * Pointers to instances of struct Trigger are stored in two ways.
 * 1. In the "trigHash" hash table (part of the sqlite3* that represents the 

  char *zProfile;            /* The profile callback routine */
  char *zProgress;           /* The progress callback routine */
  char *zAuth;               /* The authorization callback routine */
  int disableAuth;           /* Disable the authorizer if it exists */
  char *zNull;               /* Text to substitute for an SQL NULL value */
  SqlFunc *pFunc;            /* List of SQL functions */
  Tcl_Obj *pUpdateHook;      /* Update hook script (if any) */
  Tcl_Obj *pPreUpdateHook;   /* Pre-update hook script (if any) */
  Tcl_Obj *pRollbackHook;    /* Rollback hook script (if any) */
  Tcl_Obj *pWalHook;         /* WAL hook script (if any) */
  Tcl_Obj *pUnlockNotify;    /* Unlock notify script (if any) */
  SqlCollate *pCollate;      /* List of SQL collation functions */
  int rc;                    /* Return code of most recent sqlite3_exec() */
  Tcl_Obj *pCollateNeeded;   /* Collation needed script */
  SqlPreparedStmt *stmtList; /* List of prepared statements*/

  }
  if( pDb->zNull ){
    Tcl_Free(pDb->zNull);
  }
  if( pDb->pUpdateHook ){
    Tcl_DecrRefCount(pDb->pUpdateHook);
  }
  if( pDb->pPreUpdateHook ){
    Tcl_DecrRefCount(pDb->pPreUpdateHook);
  }
  if( pDb->pRollbackHook ){
    Tcl_DecrRefCount(pDb->pRollbackHook);
  }
  if( pDb->pWalHook ){
    Tcl_DecrRefCount(pDb->pWalHook);
  }
  if( pDb->pCollateNeeded ){

    assert( pDb->pUnlockNotify);
    Tcl_EvalObjEx(pDb->interp, pDb->pUnlockNotify, flags);
    Tcl_DecrRefCount(pDb->pUnlockNotify);
    pDb->pUnlockNotify = 0;
  }
}
#endif

/*
** Pre-update hook callback.
*/
static void DbPreUpdateHandler(
  void *p, 
  sqlite3 *db,
  int op,
  const char *zDb, 
  const char *zTbl, 
  sqlite_int64 iKey1,
  sqlite_int64 iKey2
){
  SqliteDb *pDb = (SqliteDb *)p;
  Tcl_Obj *pCmd;
  static const char *azStr[] = {"DELETE", "INSERT", "UPDATE"};

  assert( (SQLITE_DELETE-1)/9 == 0 );
  assert( (SQLITE_INSERT-1)/9 == 1 );
  assert( (SQLITE_UPDATE-1)/9 == 2 );
  assert( pDb->pPreUpdateHook );
  assert( db==pDb->db );
  assert( op==SQLITE_INSERT || op==SQLITE_UPDATE || op==SQLITE_DELETE );

  pCmd = Tcl_DuplicateObj(pDb->pPreUpdateHook);
  Tcl_IncrRefCount(pCmd);
  Tcl_ListObjAppendElement(0, pCmd, Tcl_NewStringObj(azStr[(op-1)/9], -1));
  Tcl_ListObjAppendElement(0, pCmd, Tcl_NewStringObj(zDb, -1));
  Tcl_ListObjAppendElement(0, pCmd, Tcl_NewStringObj(zTbl, -1));
  Tcl_ListObjAppendElement(0, pCmd, Tcl_NewWideIntObj(iKey1));
  Tcl_ListObjAppendElement(0, pCmd, Tcl_NewWideIntObj(iKey2));
  Tcl_EvalObjEx(pDb->interp, pCmd, TCL_EVAL_DIRECT);
  Tcl_DecrRefCount(pCmd);
}

static void DbUpdateHandler(
  void *p, 
  int op,
  const char *zDb, 
  const char *zTbl, 
  sqlite_int64 rowid
){
  SqliteDb *pDb = (SqliteDb *)p;
  Tcl_Obj *pCmd;
  static const char *azStr[] = {"DELETE", "INSERT", "UPDATE"};

  assert( (SQLITE_DELETE-1)/9 == 0 );
  assert( (SQLITE_INSERT-1)/9 == 1 );
  assert( (SQLITE_UPDATE-1)/9 == 2 );

  assert( pDb->pUpdateHook );
  assert( op==SQLITE_INSERT || op==SQLITE_UPDATE || op==SQLITE_DELETE );

  pCmd = Tcl_DuplicateObj(pDb->pUpdateHook);
  Tcl_IncrRefCount(pCmd);
  Tcl_ListObjAppendElement(0, pCmd, Tcl_NewStringObj(azStr[(op-1)/9], -1));

  Tcl_ListObjAppendElement(0, pCmd, Tcl_NewStringObj(zDb, -1));
  Tcl_ListObjAppendElement(0, pCmd, Tcl_NewStringObj(zTbl, -1));
  Tcl_ListObjAppendElement(0, pCmd, Tcl_NewWideIntObj(rowid));
  Tcl_EvalObjEx(pDb->interp, pCmd, TCL_EVAL_DIRECT);
  Tcl_DecrRefCount(pCmd);
}

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

/*
** This function is used by the implementations of the following database 
** handle sub-commands:
**
**   $db update_hook ?SCRIPT?
**   $db wal_hook ?SCRIPT?
**   $db commit_hook ?SCRIPT?
**   $db preupdate hook ?SCRIPT?
*/
static void DbHookCmd(
  Tcl_Interp *interp,             /* Tcl interpreter */
  SqliteDb *pDb,                  /* Database handle */
  Tcl_Obj *pArg,                  /* SCRIPT argument (or NULL) */
  Tcl_Obj **ppHook                /* Pointer to member of SqliteDb */
){
  sqlite3 *db = pDb->db;

  if( *ppHook ){
    Tcl_SetObjResult(interp, *ppHook);
    if( pArg ){
      Tcl_DecrRefCount(*ppHook);
      *ppHook = 0;
    }
  }
  if( pArg ){
    assert( !(*ppHook) );
    if( Tcl_GetCharLength(pArg)>0 ){
      *ppHook = pArg;
      Tcl_IncrRefCount(*ppHook);
    }
  }

  sqlite3_preupdate_hook(db, (pDb->pPreUpdateHook?DbPreUpdateHandler:0), pDb);
  sqlite3_update_hook(db, (pDb->pUpdateHook?DbUpdateHandler:0), pDb);
  sqlite3_rollback_hook(db, (pDb->pRollbackHook?DbRollbackHandler:0), pDb);
  sqlite3_wal_hook(db, (pDb->pWalHook?DbWalHandler:0), pDb);
}

/*
** 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:
**

    "authorizer",         "backup",            "busy",
    "cache",              "changes",           "close",
    "collate",            "collation_needed",  "commit_hook",
    "complete",           "copy",              "enable_load_extension",
    "errorcode",          "eval",              "exists",
    "function",           "incrblob",          "interrupt",
    "last_insert_rowid",  "nullvalue",         "onecolumn",
    "preupdate",
    "profile",            "progress",          "rekey",
    "restore",            "rollback_hook",     "status",
    "timeout",            "total_changes",     "trace",
    "transaction",        "unlock_notify",     "update_hook",
    "version",            "wal_hook",          0
  };
  enum DB_enum {
    DB_AUTHORIZER,        DB_BACKUP,           DB_BUSY,
    DB_CACHE,             DB_CHANGES,          DB_CLOSE,
    DB_COLLATE,           DB_COLLATION_NEEDED, DB_COMMIT_HOOK,
    DB_COMPLETE,          DB_COPY,             DB_ENABLE_LOAD_EXTENSION,
    DB_ERRORCODE,         DB_EVAL,             DB_EXISTS,
    DB_FUNCTION,          DB_INCRBLOB,         DB_INTERRUPT,
    DB_LAST_INSERT_ROWID, DB_NULLVALUE,        DB_ONECOLUMN,
    DB_PREUPDATE,
    DB_PROFILE,           DB_PROGRESS,         DB_REKEY,
    DB_RESTORE,           DB_ROLLBACK_HOOK,    DB_STATUS,
    DB_TIMEOUT,           DB_TOTAL_CHANGES,    DB_TRACE,
    DB_TRANSACTION,       DB_UNLOCK_NOTIFY,    DB_UPDATE_HOOK,
    DB_VERSION,           DB_WAL_HOOK
  };
  /* don't leave trailing commas on DB_enum, it confuses the AIX xlc compiler */

        Tcl_AppendResult(interp, sqlite3_errmsg(pDb->db), 0);
        rc = TCL_ERROR;
      }
    }
#endif
    break;
  }

  case DB_PREUPDATE: {
    static const char *azSub[] = {"count", "hook", "modified", "old", 0};
    enum DbPreupdateSubCmd {
      PRE_COUNT, PRE_HOOK, PRE_MODIFIED, PRE_OLD
    };
    int iSub;

    if( objc<3 ){
      Tcl_WrongNumArgs(interp, 2, objv, "SUB-COMMAND ?ARGS?");
    }
    if( Tcl_GetIndexFromObj(interp, objv[2], azSub, "sub-command", 0, &iSub) ){
      return TCL_ERROR;
    }

    switch( (enum DbPreupdateSubCmd)iSub ){
      case PRE_COUNT: {
        int nCol = sqlite3_preupdate_count(pDb->db);
        Tcl_SetObjResult(interp, Tcl_NewIntObj(nCol));
        break;
      }

      case PRE_HOOK: {
        if( objc>4 ){
          Tcl_WrongNumArgs(interp, 2, objv, "hook ?SCRIPT?");
          return TCL_ERROR;
        }
        DbHookCmd(interp, pDb, (objc==4 ? objv[3] : 0), &pDb->pPreUpdateHook);
        break;
      }

      case PRE_MODIFIED:
      case PRE_OLD: {
        int iIdx;
        if( objc!=4 ){
          Tcl_WrongNumArgs(interp, 3, objv, "INDEX");
          return TCL_ERROR;
        }
        if( Tcl_GetIntFromObj(interp, objv[3], &iIdx) ){
          return TCL_ERROR;
        }

        if( iSub==PRE_MODIFIED ){
          int iRes;
          rc = sqlite3_preupdate_modified(pDb->db, iIdx, &iRes);
          if( rc==SQLITE_OK ) Tcl_SetObjResult(interp, Tcl_NewIntObj(iRes));
        }else{
          sqlite3_value *pValue;
          assert( iSub==PRE_OLD );
          rc = sqlite3_preupdate_old(pDb->db, iIdx, &pValue);
          if( rc==SQLITE_OK ){
            Tcl_Obj *pObj = Tcl_NewStringObj(sqlite3_value_text(pValue), -1);
            Tcl_SetObjResult(interp, pObj);
          }
        }

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

    break;
  }

  /*
  **    $db wal_hook ?script?
  **    $db update_hook ?script?
  **    $db rollback_hook ?script?
  */
  case DB_WAL_HOOK: 
  case DB_UPDATE_HOOK: 
  case DB_ROLLBACK_HOOK: {
    sqlite3 *db = pDb->db;

    /* set ppHook to point at pUpdateHook or pRollbackHook, depending on 
    ** whether [$db update_hook] or [$db rollback_hook] was invoked.
    */
    Tcl_Obj **ppHook; 
    if( choice==DB_WAL_HOOK ) ppHook = &pDb->pWalHook;
    if( choice==DB_UPDATE_HOOK ) ppHook = &pDb->pUpdateHook;



    if( choice==DB_ROLLBACK_HOOK ) ppHook = &pDb->pRollbackHook;


    if( objc>3 ){
       Tcl_WrongNumArgs(interp, 2, objv, "?SCRIPT?");
       return TCL_ERROR;
    }














    DbHookCmd(interp, pDb, (objc==3 ? objv[2] : 0), ppHook);




    break;
  }

  /*    $db version
  **
  ** Return the version string for this database.
  */

      sqlite3FkCheck(pParse, pTab, regOldRowid, 0);
    }

    /* Delete the index entries associated with the current record.  */
    j1 = sqlite3VdbeAddOp3(v, OP_NotExists, iCur, 0, regOldRowid);
    sqlite3GenerateRowIndexDelete(pParse, pTab, iCur, aRegIdx);
  
    /* If changing the rowid value, or if there are foreign key constraints
    ** to process, delete the old record. Otherwise, add a noop OP_Delete
    ** to invoke the pre-update hook.
    */
    sqlite3VdbeAddOp3(v, OP_Delete, iCur,
        OPFLAG_ISUPDATE | ((hasFK || chngRowid) ? 0 : OPFLAG_ISNOOP),
        regNewRowid
    );
    if( !pParse->nested ){
      sqlite3VdbeChangeP4(v, -1, pTab->zName, P4_STATIC);
    }
    sqlite3VdbeJumpHere(v, j1);

    if( hasFK ){
      sqlite3FkCheck(pParse, pTab, 0, regNewRowid);
    }
  

    assert( memIsValid(pKey) );
    REGISTER_TRACE(pOp->p3, pKey);
    iKey = pKey->u.i;
  }else{
    assert( pOp->opcode==OP_InsertInt );
    iKey = pOp->p3;
  }

  if( pOp->p4.z && (db->xPreUpdateCallback || db->xUpdateCallback) ){
    assert( pC->isTable );
    assert( pC->iDb>=0 );
    zDb = db->aDb[pC->iDb].zName;
    zTbl = pOp->p4.z;
    op = ((pOp->p5 & OPFLAG_ISUPDATE) ? SQLITE_UPDATE : SQLITE_INSERT);
  }

  /* Invoke the pre-update hook, if any */
  if( db->xPreUpdateCallback 
   && pOp->p4.z 
   && (!(pOp->p5 & OPFLAG_ISUPDATE) || pC->rowidIsValid==0)
  ){
    sqlite3VdbePreUpdateHook(p, pC,
      pC->rowidIsValid ? op : SQLITE_INSERT, zDb, zTbl, iKey, iKey
    );
  }

  if( pOp->p5 & OPFLAG_NCHANGE ) p->nChange++;
  if( pOp->p5 & OPFLAG_LASTROWID ) db->lastRowid = iKey;
  if( pData->flags & MEM_Null ){
    pData->z = 0;
    pData->n = 0;
  }else{

  );
  pC->rowidIsValid = 0;
  pC->deferredMoveto = 0;
  pC->cacheStatus = CACHE_STALE;

  /* Invoke the update-hook if required. */
  if( rc==SQLITE_OK && db->xUpdateCallback && pOp->p4.z ){




    db->xUpdateCallback(db->pUpdateArg, op, zDb, zTbl, iKey);

  }
  break;
}

/* Opcode: Delete P1 P2 P3 P4 *
**
** Delete the record at which the P1 cursor is currently pointing.
**
** The cursor will be left pointing at either the next or the previous
** record in the table. If it is left pointing at the next record, then
** the next Next instruction will be a no-op.  Hence it is OK to delete
** a record from within an Next loop.
**
** If the OPFLAG_NCHANGE flag of P2 is set, then the row change count is
** incremented (otherwise not).
**
** P1 must not be pseudo-table.  It has to be a real table with
** multiple rows.
**
** If P4 is not NULL then, either the update or pre-update hook, or both,

** may be invoked. The P1 cursor must have been positioned using OP_NotFound 
** prior to invoking this opcode in this case. Specifically, if one is 
** configured, the pre-update hook is invoked if P4 is not NULL. The 
** update-hook is invoked if one is configured, P4 is not NULL, and the 
** OPFLAG_NCHANGE flag is set in P2.
**
** If the OPFLAG_ISUPDATE flag is set in P2, then P3 contains the address
** of the memory cell that contains the value that the rowid of the row will
** be set to by the update.
*/
case OP_Delete: {
  i64 iKey;
  VdbeCursor *pC;
  const char *zDb;
  const char *zTbl;
  int opflags;

  opflags = pOp->p2;
  iKey = 0;
  assert( pOp->p1>=0 && pOp->p1<p->nCursor );
  pC = p->apCsr[pOp->p1];
  assert( pC!=0 );
  assert( pC->pCursor!=0 );  /* Only valid for real tables, no pseudotables */










  /* The OP_Delete opcode always follows an OP_NotExists or OP_Last or
  ** OP_Column on the same table without any intervening operations that
  ** might move or invalidate the cursor.  Hence cursor pC is always pointing
  ** to the row to be deleted and the sqlite3VdbeCursorMoveto() operation
  ** below is always a no-op and cannot fail.  We will run it anyhow, though,
  ** to guard against future changes to the code generator.
  **/
  assert( pC->deferredMoveto==0 );
  rc = sqlite3VdbeCursorMoveto(pC);
  if( NEVER(rc!=SQLITE_OK) ) goto abort_due_to_error;

  /* If the update-hook or pre-update-hook will be invoked, set iKey to 
  ** the rowid of the row being deleted. Set zDb and zTab as well.
  */
  if( pOp->p4.z && (db->xPreUpdateCallback || db->xUpdateCallback) ){
    assert( pC->iDb>=0 );
    assert( pC->isTable );
    assert( pC->rowidIsValid );  /* lastRowid set by previous OP_NotFound */
    iKey = pC->lastRowid;
    zDb = db->aDb[pC->iDb].zName;
    zTbl = pOp->p4.z;
  }

  /* Invoke the pre-update-hook if required. */
  if( db->xPreUpdateCallback && pOp->p4.z ){
    assert( !(opflags & OPFLAG_ISUPDATE) || (aMem[pOp->p3].flags & MEM_Int) );
    sqlite3VdbePreUpdateHook(p, pC,
        (opflags & OPFLAG_ISUPDATE) ? SQLITE_UPDATE : SQLITE_DELETE, 
        zDb, zTbl, iKey,
        (opflags & OPFLAG_ISUPDATE) ? aMem[pOp->p3].u.i : iKey
    );
  }

  if( opflags & OPFLAG_ISNOOP ) break;

  sqlite3BtreeSetCachedRowid(pC->pCursor, 0);
  rc = sqlite3BtreeDelete(pC->pCursor);
  pC->cacheStatus = CACHE_STALE;

  /* Update the change-counter and invoke the update-hook if required. */
  if( opflags & OPFLAG_NCHANGE ){
    p->nChange++;
    assert( pOp->p4.z );
    if( rc==SQLITE_OK && db->xUpdateCallback ){


      db->xUpdateCallback(db->pUpdateArg, SQLITE_DELETE, zDb, zTbl, iKey);

    }

  }
  break;
}
/* Opcode: ResetCount * * * * *
**
** The value of the change counter is copied to the database handle
** change counter (returned by subsequent calls to sqlite3_changes()).
** Then the VMs internal change counter resets to 0.

** The following are allowed values for Vdbe.magic
*/
#define VDBE_MAGIC_INIT     0x26bceaa5    /* Building a VDBE program */
#define VDBE_MAGIC_RUN      0xbdf20da3    /* VDBE is ready to execute */
#define VDBE_MAGIC_HALT     0x519c2973    /* VDBE has completed execution */
#define VDBE_MAGIC_DEAD     0xb606c3c8    /* The VDBE has been deallocated */

/*
** Structure used to store the context required by the 
** sqlite3_preupdate_*() API functions.
*/
struct PreUpdate {
  VdbeCursor *pCsr;               /* Cursor to read old values from */
  int op;                         /* One of SQLITE_INSERT, UPDATE, DELETE */
  u8 *aRecord;                    /* old.* database record */
  UnpackedRecord *pUnpacked;      /* Unpacked version of aRecord[] */
};

/*
** Function prototypes
*/
void sqlite3VdbeFreeCursor(Vdbe *, VdbeCursor*);
void sqliteVdbePopStack(Vdbe*,int);
int sqlite3VdbeCursorMoveto(VdbeCursor*);
#if defined(SQLITE_DEBUG) || defined(VDBE_PROFILE)

int sqlite3VdbeMemFinalize(Mem*, FuncDef*);
const char *sqlite3OpcodeName(int);
int sqlite3VdbeMemGrow(Mem *pMem, int n, int preserve);
int sqlite3VdbeCloseStatement(Vdbe *, int);
void sqlite3VdbeFrameDelete(VdbeFrame*);
int sqlite3VdbeFrameRestore(VdbeFrame *);
void sqlite3VdbeMemStoreType(Mem *pMem);
void sqlite3VdbePreUpdateHook(
    Vdbe *, VdbeCursor *, int, const char*, const char*, i64, i64);

#ifdef SQLITE_DEBUG
void sqlite3VdbeMemPrepareToChange(Vdbe*,Mem*);
#endif

#ifndef SQLITE_OMIT_FOREIGN_KEY
int sqlite3VdbeCheckFk(Vdbe *, int);

*/
int sqlite3_data_count(sqlite3_stmt *pStmt){
  Vdbe *pVm = (Vdbe *)pStmt;
  if( pVm==0 || pVm->pResultSet==0 ) return 0;
  return pVm->nResColumn;
}

/*
** Return a pointer to static memory containing an SQL NULL value.
*/
static const Mem *columnNullValue(void){
  /* Even though the Mem structure contains an element
  ** of type i64, on certain architecture (x86) with certain compiler
  ** switches (-Os), gcc may align this Mem object on a 4-byte boundary
  ** instead of an 8-byte one. This all works fine, except that when
  ** running with SQLITE_DEBUG defined the SQLite code sometimes assert()s
  ** that a Mem structure is located on an 8-byte boundary. To prevent
  ** this assert() from failing, when building with SQLITE_DEBUG defined
  ** using gcc, force nullMem to be 8-byte aligned using the magical
  ** __attribute__((aligned(8))) macro.  */
  static const Mem nullMem 
#if defined(SQLITE_DEBUG) && defined(__GNUC__)
  __attribute__((aligned(8))) 
#endif
    = {0, "", (double)0, {0}, 0, MEM_Null, SQLITE_NULL, 0, 0, 0 };
  return &nullMem;
}

/*
** Check to see if column iCol of the given statement is valid.  If
** it is, return a pointer to the Mem for the value of that column.
** If iCol is not valid, return a pointer to a Mem which has a value
** of NULL.
*/
static Mem *columnMem(sqlite3_stmt *pStmt, int i){
  Vdbe *pVm;
  int vals;
  Mem *pOut;

  pVm = (Vdbe *)pStmt;
  if( pVm && pVm->pResultSet!=0 && i<pVm->nResColumn && i>=0 ){
    sqlite3_mutex_enter(pVm->db->mutex);
    vals = sqlite3_data_count(pStmt);
    pOut = &pVm->pResultSet[i];
  }else{
    /* If the value passed as the second argument is out of range, return
    ** a pointer to a static Mem object that contains the value SQL NULL. 














    */
    if( pVm && ALWAYS(pVm->db) ){
      sqlite3_mutex_enter(pVm->db->mutex);
      sqlite3Error(pVm->db, SQLITE_RANGE, 0);
    }
    pOut = (Mem*)columnNullValue();
  }
  return pOut;
}

/*
** This function is called after invoking an sqlite3_value_XXX function on a 
** column value (i.e. a value returned by evaluating an SQL expression in the

*/
int sqlite3_stmt_status(sqlite3_stmt *pStmt, int op, int resetFlag){
  Vdbe *pVdbe = (Vdbe*)pStmt;
  int v = pVdbe->aCounter[op-1];
  if( resetFlag ) pVdbe->aCounter[op-1] = 0;
  return v;
}

int sqlite3_preupdate_old(sqlite3 *db, int iIdx, sqlite3_value **ppValue){
  PreUpdate *p = db->pPreUpdate;
  int rc = SQLITE_OK;

  if( !p || p->op==SQLITE_INSERT ){
    rc = SQLITE_MISUSE_BKPT;
    goto preupdate_old_out;
  }
  if( iIdx>=p->pCsr->nField || iIdx<0 ){
    rc = SQLITE_RANGE;
    goto preupdate_old_out;
  }

  if( p->pUnpacked==0 ){
    KeyInfo keyinfo;
    u32 nRecord;
    u8 *aRecord;

    memset(&keyinfo, 0, sizeof(KeyInfo));
    keyinfo.db = db;
    keyinfo.enc = ENC(db);
    keyinfo.nField = p->pCsr->nField;

    rc = sqlite3BtreeDataSize(p->pCsr->pCursor, &nRecord);
    if( rc!=SQLITE_OK ) goto preupdate_old_out;
    aRecord = sqlite3DbMallocRaw(db, nRecord);
    if( !aRecord ) goto preupdate_old_out;
    rc = sqlite3BtreeData(p->pCsr->pCursor, 0, nRecord, aRecord);
    if( rc!=SQLITE_OK ){
      sqlite3DbFree(db, aRecord);
      goto preupdate_old_out;
    }

    p->pUnpacked = sqlite3VdbeRecordUnpack(&keyinfo, nRecord, aRecord, 0, 0);
    p->aRecord = aRecord;
  }

  if( iIdx>=p->pUnpacked->nField ){
    *ppValue = (sqlite3_value *)columnNullValue();
  }else{
    *ppValue = &p->pUnpacked->aMem[iIdx];
    sqlite3VdbeMemStoreType(*ppValue);
  }

 preupdate_old_out:
  sqlite3Error(db, rc, 0);
  return sqlite3ApiExit(db, rc);
}

int sqlite3_preupdate_count(sqlite3 *db){
  PreUpdate *p = db->pPreUpdate;
  return (p ? p->pCsr->nField : 0);
}

int sqlite3_preupdate_modified(sqlite3 *db, int iIdx, int *pbMod){
  PreUpdate *p = db->pPreUpdate;
  int rc = SQLITE_OK;

  if( !p || p->op!=SQLITE_UPDATE ){
    rc = SQLITE_MISUSE_BKPT;
    goto preupdate_mod_out;
  }
  if( iIdx>=p->pCsr->nField || iIdx<0 ){
    rc = SQLITE_RANGE;
    goto preupdate_mod_out;
  }
  *pbMod = 1;

 preupdate_mod_out:
  sqlite3Error(db, rc, 0);
  return sqlite3ApiExit(db, rc);
}

  assert( p->flags & UNPACKED_NEED_DESTROY );
  for(i=0, pMem=p->aMem; i<p->nField; i++, pMem++){
    /* The unpacked record is always constructed by the
    ** sqlite3VdbeUnpackRecord() function above, which makes all
    ** strings and blobs static.  And none of the elements are
    ** ever transformed, so there is never anything to delete.
    */
    if( pMem->zMalloc ) sqlite3VdbeMemRelease(pMem);
  }
  if( p->flags & UNPACKED_NEED_FREE ){
    sqlite3DbFree(p->pKeyInfo->db, p);
  }
}

/*

  assert( iVar>0 );
  if( iVar>32 ){
    v->expmask = 0xffffffff;
  }else{
    v->expmask |= ((u32)1 << (iVar-1));
  }
}

/*
** Invoke the pre-update hook. If this is an UPDATE or DELETE pre-update call,
** then cursor passed as the second argument should point to the row about
** to be update or deleted. If the application calls sqlite3_preupdate_old(),
** the required value will be read from the row the cursor points to.
*/
void sqlite3VdbePreUpdateHook(
  Vdbe *v,                        /* Vdbe pre-update hook is invoked by */
  VdbeCursor *pCsr,               /* Cursor to grab old.* values from */
  int op,                         /* SQLITE_INSERT, UPDATE or DELETE */
  const char *zDb,                /* Database name */
  const char *zTbl,               /* Table name */
  i64 iKey1,                      /* Initial key value */
  i64 iKey2                       /* Final key value */
){
  sqlite3 *db = v->db;

  PreUpdate preupdate;
  memset(&preupdate, 0, sizeof(PreUpdate));

  preupdate.pCsr = pCsr;
  preupdate.op = op;
  db->pPreUpdate = &preupdate;
  db->xPreUpdateCallback(db->pPreUpdateArg, db, op, zDb, zTbl, iKey1, iKey2);
  db->pPreUpdate = 0;
  sqlite3DbFree(db, preupdate.aRecord);
  if( preupdate.pUnpacked ){
    sqlite3VdbeDeleteUnpackedRecord(preupdate.pUnpacked);
  }
}

#      sqlite_update_hook    (tests hook-4-*)
#      sqlite_rollback_hook  (tests hook-5.*)
#
# $Id: hook.test,v 1.15 2009/04/07 14:14:23 danielk1977 Exp $

set testdir [file dirname $argv0]
source $testdir/tester.tcl
set ::testprefix hook

do_test hook-1.2 {
  db commit_hook
} {}


do_test hook-3.1 {

  }
  execsql { SELECT * FROM t1 }
} {one I}
do_test hook-6.2 {
  set ::hooks
} {COMMIT ROLLBACK}
unset ::hooks

#----------------------------------------------------------------------------
# The following tests - hook-7.* - test the pre-update hook.
#
# 7.1.1 - INSERT statement.
# 7.1.2 - INSERT INTO ... SELECT statement.
# 7.1.3 - REPLACE INTO ... (rowid conflict)
# 7.1.4 - REPLACE INTO ... (other index conflicts)
# 7.1.5 - REPLACE INTO ... (both rowid and other index conflicts)
#
# 7.2.1 - DELETE statement.
# 7.2.2 - DELETE statement that uses the truncate optimization.
#
# 7.3.1 - UPDATE statement.
# 7.3.2 - UPDATE statement that modifies the rowid.
# 7.3.3 - UPDATE OR REPLACE ... (rowid conflict).
# 7.3.4 - UPDATE OR REPLACE ... (other index conflicts)
# 7.3.4 - UPDATE OR REPLACE ... (both rowid and other index conflicts)
#
# 7.4.1 - Test that the pre-update-hook is invoked only once if a row being
#         deleted is removed by a BEFORE trigger.
#
# 7.4.2 - Test that the pre-update-hook is invoked if a BEFORE trigger 
#         removes a row being updated. In this case the update hook should
#         be invoked with SQLITE_INSERT as the opcode when inserting the
#         new version of the row.
#         
# TODO: Short records (those created before a column is added to a table 
#       using ALTER TABLE)
#

proc do_preupdate_test {tn sql x} {
  set X [list]
  foreach elem $x {lappend X $elem}
  uplevel do_test $tn [list "
    set ::preupdate \[list\]
    execsql { $sql }
    set ::preupdate
  "] [list $X]
}

proc preupdate_hook {args} {
  set type [lindex $args 0]
  eval lappend ::preupdate $args
  if {$type != "SQLITE_INSERT"} {
    for {set i 0} {$i < [db preupdate count]} {incr i} {
      lappend ::preupdate [db preupdate old $i]
    }
  }
}

db close
forcedelete test.db
sqlite3 db test.db
db preupdate hook preupdate_hook

# Set up a schema to use for tests 7.1.* to 7.3.*.
do_execsql_test 7.0 { 
  CREATE TABLE t1(a, b); 
  CREATE TABLE t2(x, y); 
  CREATE TABLE t3(i, j, UNIQUE(i));

  INSERT INTO t2 VALUES('a', 'b');
  INSERT INTO t2 VALUES('c', 'd');

  INSERT INTO t3 VALUES(4, 16);
  INSERT INTO t3 VALUES(5, 25);
  INSERT INTO t3 VALUES(6, 36);
} 

do_preupdate_test 7.1.1 {
  INSERT INTO t1 VALUES('x', 'y')
} {INSERT main t1 1 1}

# 7.1.2.1 does not use the xfer optimization. 7.1.2.2 does.
do_preupdate_test 7.1.2.1 {
  INSERT INTO t1 SELECT y, x FROM t2;
} {INSERT main t1 2 2 INSERT main t1 3 3}
do_preupdate_test 7.1.2.2 {
  INSERT INTO t1 SELECT * FROM t2;
} {INSERT main t1 4 4 INSERT main t1 5 5}

do_preupdate_test 7.1.3 {
  REPLACE INTO t1(rowid, a, b) VALUES(1, 1, 1);
} {
  DELETE main t1 1 1   x y
  INSERT main t1 1 1
}

do_preupdate_test 7.1.4 {
  REPLACE INTO t3 VALUES(4, NULL);
} {
  DELETE main t3 1 1   4 16
  INSERT main t3 4 4
}

do_preupdate_test 7.1.5 {
  REPLACE INTO t3(rowid, i, j) VALUES(2, 6, NULL);
} {
  DELETE main t3 2 2  5 25
  DELETE main t3 3 3  6 36
  INSERT main t3 2 2
}

do_execsql_test 7.2.0 { SELECT rowid FROM t1 } {1 2 3 4 5}

do_preupdate_test 7.2.1 {
  DELETE FROM t1 WHERE rowid = 3
} {
  DELETE main t1 3 3  d c
}
do_preupdate_test 7.2.2 {
  DELETE FROM t1
} {
  DELETE main t3 1 1   1 1
  DELETE main t3 2 2   b a
  DELETE main t3 4 4   a b
  DELETE main t3 5 5   c d
}

do_execsql_test 7.3.0 { 
  DELETE FROM t1;
  DELETE FROM t2;
  DELETE FROM t3;

  INSERT INTO t2 VALUES('a', 'b');
  INSERT INTO t2 VALUES('c', 'd');

  INSERT INTO t3 VALUES(4, 16);
  INSERT INTO t3 VALUES(5, 25);
  INSERT INTO t3 VALUES(6, 36);
}

do_preupdate_test 7.3.1 {
  UPDATE t2 SET y = y||y;
} {
  UPDATE main t2 1 1   a b
  UPDATE main t2 2 2   c d
}

do_preupdate_test 7.3.2 {
  UPDATE t2 SET rowid = rowid-1;
} {
  UPDATE main t2 1 0   a bb
  UPDATE main t2 2 1   c dd
}

do_preupdate_test 7.3.3 {
  UPDATE OR REPLACE t2 SET rowid = 1 WHERE x = 'a'
} {
  DELETE main t2 1 1   c dd
  UPDATE main t2 0 1   a bb
}

do_preupdate_test 7.3.4.1 {
  UPDATE OR REPLACE t3 SET i = 5 WHERE i = 6
} {
  DELETE main t3 2 2   5 25
  UPDATE main t3 3 3   6 36
}

do_execsql_test 7.3.4.2 {
  INSERT INTO t3 VALUES(10, 100);
  SELECT rowid, * FROM t3;
} {1 4 16   3 5 36   4 10 100}

do_preupdate_test 7.3.5 {
  UPDATE OR REPLACE t3 SET rowid = 1, i = 5 WHERE j = 100;
} {
  DELETE main t3 1 1    4  16
  DELETE main t3 3 3    5  36
  UPDATE main t3 4 1   10 100
}

do_execsql_test 7.4.1.0 {
  CREATE TABLE t4(a, b);
  INSERT INTO t4 VALUES('a', 1);
  INSERT INTO t4 VALUES('b', 2);
  INSERT INTO t4 VALUES('c', 3);

  CREATE TRIGGER t4t BEFORE DELETE ON t4 BEGIN
    DELETE FROM t4 WHERE b = 1;
  END;
}

do_preupdate_test 7.4.1.1 {
  DELETE FROM t4 WHERE b = 3
} {
  DELETE main t4 1 1   a 1
  DELETE main t4 3 3   c 3
}

do_execsql_test 7.4.1.2 {
  INSERT INTO t4(rowid, a, b) VALUES(1, 'a', 1);
  INSERT INTO t4(rowid, a, b) VALUES(3, 'c', 3);
}
do_preupdate_test 7.4.1.3 {
  DELETE FROM t4 WHERE b = 1
} {
  DELETE main t4 1 1   a 1
}

do_execsql_test 7.4.2.0 {
  CREATE TABLE t5(a, b);
  INSERT INTO t5 VALUES('a', 1);
  INSERT INTO t5 VALUES('b', 2);
  INSERT INTO t5 VALUES('c', 3);

  CREATE TRIGGER t5t BEFORE UPDATE ON t5 BEGIN
    DELETE FROM t5 WHERE b = 1;
  END;
}
do_preupdate_test 7.4.2.1 {
  UPDATE t5 SET b = 4 WHERE a = 'c'
} {
  DELETE main t5 1 1   a 1
  UPDATE main t5 3 3   c 3
}

do_execsql_test 7.4.2.2 {
  INSERT INTO t5(rowid, a, b) VALUES(1, 'a', 1);
}

do_preupdate_test 7.4.2.3 {
  UPDATE t5 SET b = 5 WHERE a = 'a'
} {
  DELETE main t5 1 1   a 1
}

do_execsql_test 7.5.1.0 {
  CREATE TABLE t7(a, b);
  INSERT INTO t7 VALUES('one', 'two');
  INSERT INTO t7 VALUES('three', 'four');
  ALTER TABLE t7 ADD COLUMN c DEFAULT NULL;
}

do_preupdate_test 7.5.1.1 {
  DELETE FROM t7 WHERE a = 'one'
} {
  DELETE main t7 1 1   one two {}
}

do_preupdate_test 7.5.1.2 {
  UPDATE t7 SET b = 'five'
} {
  UPDATE main t7 2 2   three four {}
}

do_execsql_test 7.5.2.0 {
  CREATE TABLE t8(a, b);
  INSERT INTO t8 VALUES('one', 'two');
  INSERT INTO t8 VALUES('three', 'four');
  ALTER TABLE t8 ADD COLUMN c DEFAULT 'xxx';
}

do_preupdate_test 7.5.2.1 {
  DELETE FROM t8 WHERE a = 'one'
} {
  DELETE main t8 1 1   one two xxx
}

do_preupdate_test 7.5.2.2 {
  UPDATE t8 SET b = 'five'
} {
  UPDATE main t8 2 2   three four xxx
}

finish_test

  set v [catch {sqlite3 bogus} msg]
  regsub {really_sqlite3} $msg {sqlite3} msg
  lappend v $msg
} [list 1 "wrong # args: should be \"$r\""]
do_test tcl-1.2 {
  set v [catch {db bogus} msg]
  lappend v $msg
} {1 {bad option "bogus": must be authorizer, backup, busy, cache, changes, close, collate, collation_needed, commit_hook, complete, copy, enable_load_extension, errorcode, eval, exists, function, incrblob, interrupt, last_insert_rowid, nullvalue, onecolumn, preupdate, profile, progress, rekey, restore, rollback_hook, status, timeout, total_changes, trace, transaction, unlock_notify, update_hook, version, or wal_hook}}
do_test tcl-1.2.1 {
  set v [catch {db cache bogus} msg]
  lappend v $msg
} {1 {bad option "bogus": must be flush or size}}
do_test tcl-1.2.2 {
  set v [catch {db cache} msg]
  lappend v $msg