SQLite

#ifndef SQLITE_OMIT_TRIGGER

/*
** Deferred and Immediate FKs
** --------------------------
**
** Foreign keys in SQLite come in two flavours: deferred and immediate.
** If an immediate foreign key constraint is violated, an OP_Halt is 
** executed and the current statement transaction rolled back. If a 
** deferred foreign key constraint is violated, no action is taken 
** immediately. However if the application attempts to commit the 
** transaction before fixing the constraint violation, the attempt fails.
**
** Deferred constraints are implemented using a simple counter associated
** with the database handle. The counter is set to zero each time a 
** database transaction is opened. Each time a statement is executed 

**
** Despite these problems, this approach is adopted as it seems simpler
** than the alternatives.
**
** INSERT operations:
**
**   I.1) For each FK for which the table is the child table, search
**        the parent table for a match. If none is found, throw an 
**        exception for an immediate FK, or increment the counter for a
**        deferred FK.
**
**   I.2) For each deferred FK for which the table is the parent table, 
**        search the child table for rows that correspond to the new
**        row in the parent table. Decrement the counter for each row
**        found (as the constraint is now satisfied).
**
** DELETE operations:
**
**   D.1) For each deferred FK for which the table is the child table, 
**        search the parent table for a row that corresponds to the 
**        deleted row in the child table. If such a row is not found, 
**        decrement the counter.
**
**   D.2) For each FK for which the table is the parent table, search 
**        the child table for rows that correspond to the deleted row 
**        in the parent table. For each found, throw an exception for an
**        immediate FK, or increment the counter for a deferred FK.
**
** UPDATE operations:
**
**   An UPDATE command requires that all 4 steps above are taken, but only
**   for FK constraints for which the affected columns are actually 
**   modified (values must be compared at runtime).
**

      ** column of pFKey, then this index is a winner.  */

      if( zKey==0 ){
        /* If zKey is NULL, then this foreign key is implicitly mapped to 
        ** the PRIMARY KEY of table pParent. The PRIMARY KEY index may be 
        ** identified by the test (Index.autoIndex==2).  */
        if( pIdx->autoIndex==2 ){
          if( aiCol ) memcpy(aiCol, pIdx->aiColumn, sizeof(int)*nCol);



          break;
        }
      }else{
        /* If zKey is non-NULL, then this foreign key was declared to
        ** map to an explicit list of columns in table pParent. Check if this
        ** index matches those columns.  */
        int i, j;

void sqlite3VdbeFrameDelete(VdbeFrame*);
int sqlite3VdbeFrameRestore(VdbeFrame *);
#ifdef SQLITE_ENABLE_MEMORY_MANAGEMENT
int sqlite3VdbeReleaseBuffers(Vdbe *p);
#endif

#ifndef SQLITE_OMIT_FOREIGN_KEY
int sqlite3VdbeCheckDeferred(Vdbe *);
#else
# define sqlite3VdbeCheckDeferred(p) 0
#endif

#ifndef SQLITE_OMIT_SHARED_CACHE
void sqlite3VdbeMutexArrayEnter(Vdbe *p);
#else
# define sqlite3VdbeMutexArrayEnter(p)
#endif