SQLite

#ifndef SQLITE_OMIT_CHECK
    { "ignore_check_constraints", SQLITE_IgnoreChecks  },
#endif
    /* The following is VERY experimental */
    { "writable_schema",          SQLITE_WriteSchema|SQLITE_RecoveryMode },
    { "omit_readlock",            SQLITE_NoReadlock    },

    /* For testing purposes only */
    { "omit_flattener",           SQLITE_OmitFlattener },

    /* TODO: Maybe it shouldn't be possible to change the ReadUncommitted
    ** flag if there are any active statements. */
    { "read_uncommitted",         SQLITE_ReadUncommitted },
    { "recursive_triggers",       SQLITE_RecTriggers },

    /* This flag may only be set if both foreign-key and trigger support
    ** are present in the build.  */

      assert( pTab && pExpr->pTab==pTab );
      if( pS ){
        /* The "table" is actually a sub-select or a view in the FROM clause
        ** of the SELECT statement. Return the declaration type and origin
        ** data for the result-set column of the sub-select.
        */
        if( iCol>=0 && ALWAYS(iCol<pS->pEList->nExpr) ){
          /* If iCol is less than zero, then the expression requests the
          ** rowid of the sub-select or view. This expression is legal (see 
          ** test case misc2.2.2) - it always evaluates to NULL.
          */
          NameContext sNC;
          Expr *p = pS->pEList->a[iCol].pExpr;
          sNC.pSrcList = pS->pSrc;

**        aggregates.
**
**  (10)  The subquery does not use aggregates or the outer query does not
**        use LIMIT.
**
**  (11)  The subquery and the outer query do not both have ORDER BY clauses.
**
**  (**)  Not implemented.  Subsumed into restriction (3).  Was previously
**        a separate restriction deriving from ticket #350.
**
**  (13)  The subquery and outer query do not both use LIMIT
**
**  (14)  The subquery does not use OFFSET
**
**  (15)  The outer query is not part of a compound select or the

  struct SrcList_item *pSubitem;   /* The subquery */
  sqlite3 *db = pParse->db;

  /* Check to see if flattening is permitted.  Return 0 if not.
  */
  assert( p!=0 );
  assert( p->pPrior==0 );  /* Unable to flatten compound queries */

  /* The "PRAGMA omit_flattener=ON" statement disables query flattening for
  ** testing purposes.  The only reason to disable the query flattener is
  ** to verify that we get the same answer with and without the flattener.
  ** In production use, there is never a reason to turn the flattener off. */
  if( db->flags & SQLITE_OmitFlattener ) return 0;

  pSrc = p->pSrc;
  assert( pSrc && iFrom>=0 && iFrom<pSrc->nSrc );
  pSubitem = &pSrc->a[iFrom];
  iParent = pSubitem->iCursor;
  pSub = pSubitem->pSelect;
  assert( pSub!=0 );
  if( isAgg && subqueryIsAgg ) return 0;                 /* Restriction (1)  */

                                          /*   result set is empty */
#define SQLITE_SqlTrace       0x00000200  /* Debug print SQL as it executes */
#define SQLITE_VdbeListing    0x00000400  /* Debug listings of VDBE programs */
#define SQLITE_WriteSchema    0x00000800  /* OK to update SQLITE_MASTER */
#define SQLITE_NoReadlock     0x00001000  /* Readlocks are omitted when 
                                          ** accessing read-only databases */
#define SQLITE_IgnoreChecks   0x00002000  /* Do not enforce check constraints */
#define SQLITE_ReadUncommitted 0x0004000  /* For shared-cache mode */
#define SQLITE_LegacyFileFmt  0x00008000  /* Create new databases in format 1 */
#define SQLITE_FullFSync      0x00010000  /* Use full fsync on the backend */
#define SQLITE_LoadExtension  0x00020000  /* Enable load_extension */

#define SQLITE_RecoveryMode   0x00040000  /* Ignore schema errors */
#define SQLITE_ReverseOrder   0x00100000  /* Reverse unordered SELECTs */
#define SQLITE_RecTriggers    0x00200000  /* Enable recursive triggers */
#define SQLITE_ForeignKeys    0x00400000  /* Enforce foreign key constraints */
#define SQLITE_OmitFlattener  0x00800000  /* Do not flatten queries */

/*
** Possible values for the sqlite.magic field.
** The numbers are obtained at random and have no special meaning, other
** than being distinct from one another.
*/
#define SQLITE_MAGIC_OPEN     0xa029a697  /* Database is open */