SQLite

}

/*
** Add code to implement the OFFSET
*/
static void codeOffset(
  Vdbe *v,          /* Generate code into this VM */
  int iOffset,      /* Register holding the offset counter */
  int iContinue     /* Jump here to skip the current record */
){
  if( iOffset>0 && iContinue!=0 ){
    int addr;
    sqlite3VdbeAddOp2(v, OP_AddImm, iOffset, -1);
    addr = sqlite3VdbeAddOp1(v, OP_IfNeg, iOffset);
    sqlite3VdbeAddOp2(v, OP_Goto, 0, iContinue);
    VdbeComment((v, "skip OFFSET records"));
    sqlite3VdbeJumpHere(v, addr);
  }
}

/*

  int iParm = pDest->iSDParm; /* First argument to disposal method */
  int nResultCol;             /* Number of result columns */

  assert( v );
  assert( pEList!=0 );
  hasDistinct = pDistinct ? pDistinct->eTnctType : WHERE_DISTINCT_NOOP;
  if( pOrderBy==0 && !hasDistinct ){
    codeOffset(v, p->iOffset, iContinue);
  }

  /* Pull the requested columns.
  */
  nResultCol = pEList->nExpr;
  if( pDest->iSdst==0 ){
    pDest->iSdst = pParse->nMem+1;

      default: {
        assert( pDistinct->eTnctType==WHERE_DISTINCT_UNORDERED );
        codeDistinct(pParse, pDistinct->tabTnct, iContinue, nResultCol, regResult);
        break;
      }
    }
    if( pOrderBy==0 ){
      codeOffset(v, p->iOffset, iContinue);
    }
  }

  switch( eDest ){
    /* In this mode, write each query result to the key of the temporary
    ** table iParm.
    */

    regRowid = sqlite3GetTempReg(pParse);
  }
  if( p->selFlags & SF_UseSorter ){
    int regSortOut = ++pParse->nMem;
    int ptab2 = pParse->nTab++;
    sqlite3VdbeAddOp3(v, OP_OpenPseudo, ptab2, regSortOut, pOrderBy->nExpr+2);
    addr = 1 + sqlite3VdbeAddOp2(v, OP_SorterSort, iTab, addrBreak);
    codeOffset(v, p->iOffset, addrContinue);
    sqlite3VdbeAddOp2(v, OP_SorterData, iTab, regSortOut);
    sqlite3VdbeAddOp3(v, OP_Column, ptab2, pOrderBy->nExpr+1, regRow);
    sqlite3VdbeChangeP5(v, OPFLAG_CLEARCACHE);
  }else{
    addr = 1 + sqlite3VdbeAddOp2(v, OP_Sort, iTab, addrBreak);
    codeOffset(v, p->iOffset, addrContinue);
    sqlite3VdbeAddOp3(v, OP_Column, iTab, pOrderBy->nExpr+1, regRow);
  }
  switch( eDest ){
    case SRT_Table:
    case SRT_EphemTab: {
      testcase( eDest==SRT_Table );
      testcase( eDest==SRT_EphemTab );

** keywords.  Or NULL if those keywords are omitted. iLimit and iOffset 
** are the integer memory register numbers for counters used to compute 
** the limit and offset.  If there is no limit and/or offset, then 
** iLimit and iOffset are negative.
**
** This routine changes the values of iLimit and iOffset only if
** a limit or offset is defined by pLimit and pOffset.  iLimit and
** iOffset should have been preset to appropriate default values (zero)
** prior to calling this routine.
**
** The iOffset register (if it exists) is initialized to the value
** of the OFFSET.  The iLimit register is initialized to LIMIT.  Register
** iOffset+1 is initialized to LIMIT+OFFSET.
**
** Only if pLimit!=0 or pOffset!=0 do the limit registers get
** redefined.  The UNION ALL operator uses this property to force
** the reuse of the same limit and offset registers across multiple
** SELECT statements.
*/
static void computeLimitRegisters(Parse *pParse, Select *p, int iBreak){
  Vdbe *v = 0;

  ** no rows.
  */
  sqlite3ExprCacheClear(pParse);
  assert( p->pOffset==0 || p->pLimit!=0 );
  if( p->pLimit ){
    p->iLimit = iLimit = ++pParse->nMem;
    v = sqlite3GetVdbe(pParse);
    assert( v!=0 );
    if( sqlite3ExprIsInteger(p->pLimit, &n) ){
      sqlite3VdbeAddOp2(v, OP_Integer, n, iLimit);
      VdbeComment((v, "LIMIT counter"));
      if( n==0 ){
        sqlite3VdbeAddOp2(v, OP_Goto, 0, iBreak);
      }else if( n>=0 && p->nSelectRow>(u64)n ){
        p->nSelectRow = n;

  int iQueue;                   /* The Queue table */
  int iDistinct = 0;            /* To ensure unique results if UNION */
  int eDest = SRT_Table;        /* How to write to Queue */
  SelectDest destQueue;         /* SelectDest targetting the Queue table */
  int i;                        /* Loop counter */
  int rc;                       /* Result code */
  ExprList *pOrderBy;           /* The ORDER BY clause */
  Expr *pLimit, *pOffset;       /* Saved LIMIT and OFFSET */
  int regLimit, regOffset;      /* Registers used by LIMIT and OFFSET */

  /* Obtain authorization to do a recursive query */
  if( sqlite3AuthCheck(pParse, SQLITE_RECURSIVE, 0, 0, 0) ) return;

  /* Process the LIMIT and OFFSET clauses, if they exist */
  addrBreak = sqlite3VdbeMakeLabel(v);
  computeLimitRegisters(pParse, p, addrBreak);



  pLimit = p->pLimit;
  pOffset = p->pOffset;
  regLimit = p->iLimit;
  regOffset = p->iOffset;
  p->pLimit = p->pOffset = 0;

  p->iLimit = p->iOffset = 0;


  /* Locate the cursor number of the Current table */
  for(i=0; ALWAYS(i<pSrc->nSrc); i++){
    if( pSrc->a[i].isRecursive ){
      iCurrent = pSrc->a[i].iCursor;
      break;
    }

  }else{
    sqlite3VdbeAddOp2(v, OP_RowData, iQueue, regCurrent);
  }
  sqlite3VdbeAddOp1(v, OP_Delete, iQueue);

  /* Output the single row in Current */
  addrCont = sqlite3VdbeMakeLabel(v);
  codeOffset(v, regOffset, addrCont);
  selectInnerLoop(pParse, p, p->pEList, iCurrent,
      0, 0, pDest, addrCont, addrBreak);
  if( regLimit ) sqlite3VdbeAddOp3(v, OP_IfZero, regLimit, addrBreak, -1);
  sqlite3VdbeResolveLabel(v, addrCont);

  /* Execute the recursive SELECT taking the single row in Current as
  ** the value for the recursive-table. Store the results in the Queue.
  */
  p->pPrior = 0;
  sqlite3Select(pParse, p, &destQueue);
  assert( p->pPrior==0 );
  p->pPrior = pSetup;

  /* Keep running the loop until the Queue is empty */
  sqlite3VdbeAddOp2(v, OP_Goto, 0, addrTop);
  sqlite3VdbeResolveLabel(v, addrBreak);

end_of_recursive_query:
  p->pOrderBy = pOrderBy;
  p->pLimit = pLimit;
  p->pOffset = pOffset;
  return;
}
#endif

/* Forward references */
static int multiSelectOrderBy(
  Parse *pParse,        /* Parsing context */

    sqlite3VdbeAddOp3(v, OP_Copy, pIn->iSdst, regPrev+1, pIn->nSdst-1);
    sqlite3VdbeAddOp2(v, OP_Integer, 1, regPrev);
  }
  if( pParse->db->mallocFailed ) return 0;

  /* Suppress the first OFFSET entries if there is an OFFSET clause
  */
  codeOffset(v, p->iOffset, iContinue);

  switch( pDest->eDest ){
    /* Store the result as data using a unique key.
    */
    case SRT_Table:
    case SRT_EphemTab: {
      int r1 = sqlite3GetTempReg(pParse);

       UNION ALL
       SELECT edge.xto, edge.seq FROM edge, ancest
        WHERE edge.xfrom=ancest.id
        ORDER BY 2
      )
  SELECT * FROM ancest;
} {0 0 1 10 2 20 3 30 4 40 4 40 5 50 6 60 7 70 7 70 8 80 8 80 8 80 8 80 9 90 9 90 9 90 9 90}
do_execsql_test 5.2.3 {
  WITH RECURSIVE
    ancest(id, mtime) AS
      (VALUES(0, 0)
       UNION ALL
       SELECT edge.xto, edge.seq FROM edge, ancest
        WHERE edge.xfrom=ancest.id
        ORDER BY 2 LIMIT 4 OFFSET 2
      )
  SELECT * FROM ancest;
} {2 20 3 30 4 40 4 40}

do_catchsql_test 5.3 {
  WITH i(x) AS ( VALUES(1) UNION ALL SELECT x+1 FROM i LIMIT 5)
  SELECT x FROM i;
} {0 {1 2 3 4 5}}

do_execsql_test 5.4 {
  WITH i(x) AS ( VALUES(1) UNION ALL SELECT (x+1)%10 FROM i)
  SELECT x FROM i LIMIT 20;
} {1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0}

do_execsql_test 5.5 {