SQLite

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

  }else{ 
    assert( pDest->nSdst==nResultCol );

  }
  regResult = pDest->iSdst;
  if( srcTab>=0 ){
    for(i=0; i<nResultCol; i++){
      sqlite3VdbeAddOp3(v, OP_Column, srcTab, i, regResult+i);
      VdbeComment((v, "%s", pEList->a[i].zName));
    }

  }

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








    case SRT_Union: {
      int r1;
      r1 = sqlite3GetTempReg(pParse);
      sqlite3VdbeAddOp3(v, OP_MakeRecord, regResult, nResultCol, r1);












      sqlite3VdbeAddOp2(v, OP_IdxInsert, iParm, r1);
      sqlite3ReleaseTempReg(pParse, r1);
      break;
    }

    /* Construct a record from the query result, but instead of
    ** saving that record, use it as a key to delete elements from

        sqlite3VdbeAddOp1(v, OP_Yield, pDest->iSDParm);
      }else{
        sqlite3VdbeAddOp2(v, OP_ResultRow, regResult, nResultCol);
        sqlite3ExprCacheAffinityChange(pParse, regResult, nResultCol);
      }
      break;
    }

#ifndef SQLITE_OMIT_CTE
    /* Write the results into a priority queue that is order according to
    ** pDest->pOrderBy (in pSO).  pDest->iSDParm (in iParm) is the cursor for an
    ** index with pSO->nExpr+2 columns.  Build a key using pSO for the first
    ** pSO->nExpr columns, then make sure all keys are unique by adding a
    ** final OP_Sequence column.  The last column is the record as a blob.
    */
    case SRT_DistQueue:
    case SRT_Queue: {
      int nKey;
      int r1, r2, r3;
      int addrTest = 0;
      ExprList *pSO;
      pSO = pDest->pOrderBy;
      assert( pSO );
      nKey = pSO->nExpr;
      r1 = sqlite3GetTempReg(pParse);
      r2 = sqlite3GetTempRange(pParse, nKey+2);
      r3 = r2+nKey+1;
      sqlite3VdbeAddOp3(v, OP_MakeRecord, regResult, nResultCol, r3);
      if( eDest==SRT_DistQueue ){
        /* If the destination is DistQueue, then cursor (iParm+1) is open
        ** on a second ephemeral index that holds all values every previously
        ** added to the queue.  Only add this new value if it has never before
        ** been added */
        addrTest = sqlite3VdbeAddOp4Int(v, OP_Found, iParm+1, 0, r3, 0);
        sqlite3VdbeAddOp2(v, OP_IdxInsert, iParm+1, r3);
      }
      for(i=0; i<nKey; i++){
        sqlite3VdbeAddOp2(v, OP_SCopy,
                          regResult + pSO->a[i].u.x.iOrderByCol - 1,
                          r2+i);
      }
      sqlite3VdbeAddOp2(v, OP_Sequence, iParm, r2+nKey);
      sqlite3VdbeAddOp3(v, OP_MakeRecord, r2, nKey+2, r1);
      sqlite3VdbeAddOp2(v, OP_IdxInsert, iParm, r1);
      if( addrTest ) sqlite3VdbeJumpHere(v, addrTest);
      sqlite3ReleaseTempReg(pParse, r1);
      sqlite3ReleaseTempRange(pParse, r2, nKey+2);
      break;
    }
#endif /* SQLITE_OMIT_CTE */



#if !defined(SQLITE_OMIT_TRIGGER)
    /* Discard the results.  This is used for SELECT statements inside
    ** the body of a TRIGGER.  The purpose of such selects is to call
    ** user-defined functions that have side effects.  We do not care
    ** about the actual results of the select.
    */

** then the KeyInfo structure is appropriate for initializing a virtual
** index to implement a DISTINCT test.
**
** Space to hold the KeyInfo structure is obtain from malloc.  The calling
** function is responsible for seeing that this structure is eventually
** freed.
*/
static KeyInfo *keyInfoFromExprList(Parse *pParse, ExprList *pList, int nExtra){
  int nExpr;
  KeyInfo *pInfo;
  struct ExprList_item *pItem;
  sqlite3 *db = pParse->db;
  int i;

  nExpr = pList->nExpr;
  pInfo = sqlite3KeyInfoAlloc(db, nExpr+nExtra, 1);
  if( pInfo ){
    assert( sqlite3KeyInfoIsWriteable(pInfo) );
    for(i=0, pItem=pList->a; i<nExpr; i++, pItem++){
      CollSeq *pColl;
      pColl = sqlite3ExprCollSeq(pParse, pItem->pExpr);
      if( !pColl ) pColl = db->pDfltColl;
      pInfo->aColl[i] = pColl;

**
**
** There is exactly one reference to the recursive-table in the FROM clause
** of recursive-query, marked with the SrcList->a[].isRecursive flag.
**
** The setup-query runs once to generate an initial set of rows that go
** into a Queue table.  Rows are extracted from the Queue table one by
** one.  Each row extracted from Queue is output to pDest.  Then the single
** extracted row (now in the iCurrent table) becomes the content of the
** recursive-table for a recursive-query run.  The output of the recursive-query
** is added back into the Queue table.  Then another row is extracted from Queue
** and the iteration continues until the Queue table is empty.
**
** If the compound query operator is UNION then no duplicate rows are ever
** inserted into the Queue table.  The iDistinct table keeps a copy of all rows
** that have ever been inserted into Queue and causes duplicates to be
** discarded.  If the operator is UNION ALL, then duplicates are allowed.

  int regCurrent;               /* Register holding Current table */
  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 */

  /* Obtain authorization to do a recursive query */
  if( sqlite3AuthCheck(pParse, SQLITE_RECURSIVE, 0, 0, 0) ) return;
  addrBreak = sqlite3VdbeMakeLabel(v);



  /* Check that there is no ORDER BY or LIMIT clause. Neither of these 
  ** are currently supported on recursive queries.
  */
  assert( p->pOffset==0 || p->pLimit );
  if( /*p->pOrderBy ||*/ p->pLimit ){
    sqlite3ErrorMsg(pParse, "%s in a recursive query",
        p->pOrderBy ? "ORDER BY" : "LIMIT"
    );
    return;
  }

  /* 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;
    }
  }

  /* Detach the ORDER BY clause from the compound SELECT */
  pOrderBy = p->pOrderBy;
  p->pOrderBy = 0;

  /* Allocate cursors numbers for Queue and Distinct.  The cursor number for
  ** the Distinct table must be exactly one greater than Queue in order
  ** for the SRT_DistTable and SRT_DistQueue destinations to work. */
  iQueue = pParse->nTab++;
  if( p->op==TK_UNION ){

    eDest = pOrderBy ? SRT_DistQueue : SRT_DistTable;

    iDistinct = pParse->nTab++;
  }else{
    eDest = pOrderBy ? SRT_Queue : SRT_Table;
  }
  sqlite3SelectDestInit(&destQueue, eDest, iQueue);

  /* Allocate cursors for Current, Queue, and Distinct. */
  regCurrent = ++pParse->nMem;
  sqlite3VdbeAddOp3(v, OP_OpenPseudo, iCurrent, regCurrent, nCol);
  if( pOrderBy ){
    KeyInfo *pKeyInfo = keyInfoFromExprList(pParse, pOrderBy, 1);
    sqlite3VdbeAddOp4(v, OP_OpenEphemeral, iQueue, pOrderBy->nExpr+2, 0,
                      (char*)pKeyInfo, P4_KEYINFO);
    destQueue.pOrderBy = pOrderBy;
  }else{
    sqlite3VdbeAddOp2(v, OP_OpenEphemeral, iQueue, nCol);
  }
  VdbeComment((v, "Queue table"));
  if( iDistinct ){
    p->addrOpenEphm[0] = sqlite3VdbeAddOp2(v, OP_OpenEphemeral, iDistinct, 0);
    p->selFlags |= SF_UsesEphemeral;
  }

  /* Store the results of the setup-query in Queue. */
  rc = sqlite3Select(pParse, pSetup, &destQueue);
  if( rc ) goto end_of_recursive_query;

  /* Find the next row in the Queue and output that row */
  addrTop = sqlite3VdbeAddOp2(v, OP_Rewind, iQueue, addrBreak);




  /* Transfer the next row in Queue over to Current */
  sqlite3VdbeAddOp1(v, OP_NullRow, iCurrent); /* To reset column cache */
  if( pOrderBy ){
    sqlite3VdbeAddOp3(v, OP_Column, iQueue, pOrderBy->nExpr+1, regCurrent);
  }else{
    sqlite3VdbeAddOp2(v, OP_RowData, iQueue, regCurrent);
  }
  sqlite3VdbeAddOp1(v, OP_Delete, iQueue);

  /* Output the single row in Current */
  addrCont = sqlite3VdbeMakeLabel(v);
  selectInnerLoop(pParse, p, p->pEList, iCurrent,
      0, 0, pDest, addrCont, addrBreak);
  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;
  return;
}
#endif

/* Forward references */
static int multiSelectOrderBy(
  Parse *pParse,        /* Parsing context */
  Select *p,            /* The right-most of SELECTs to be coded */

      Expr *pE = pFunc->pExpr;
      assert( !ExprHasProperty(pE, EP_xIsSelect) );
      if( pE->x.pList==0 || pE->x.pList->nExpr!=1 ){
        sqlite3ErrorMsg(pParse, "DISTINCT aggregates must have exactly one "
           "argument");
        pFunc->iDistinct = -1;
      }else{
        KeyInfo *pKeyInfo = keyInfoFromExprList(pParse, pE->x.pList, 0);
        sqlite3VdbeAddOp4(v, OP_OpenEphemeral, pFunc->iDistinct, 0, 0,
                          (char*)pKeyInfo, P4_KEYINFO);
      }
    }
  }
}

  ** extracted in pre-sorted order.  If that is the case, then the
  ** OP_OpenEphemeral instruction will be changed to an OP_Noop once
  ** we figure out that the sorting index is not needed.  The addrSortIndex
  ** variable is used to facilitate that change.
  */
  if( pOrderBy ){
    KeyInfo *pKeyInfo;
    pKeyInfo = keyInfoFromExprList(pParse, pOrderBy, 0);
    pOrderBy->iECursor = pParse->nTab++;
    p->addrOpenEphm[2] = addrSortIndex =
      sqlite3VdbeAddOp4(v, OP_OpenEphemeral,
                           pOrderBy->iECursor, pOrderBy->nExpr+2, 0,
                           (char*)pKeyInfo, P4_KEYINFO);
  }else{
    addrSortIndex = -1;

  /* Open a virtual index to use for the distinct set.
  */
  if( p->selFlags & SF_Distinct ){
    sDistinct.tabTnct = pParse->nTab++;
    sDistinct.addrTnct = sqlite3VdbeAddOp4(v, OP_OpenEphemeral,
                                sDistinct.tabTnct, 0, 0,
                                (char*)keyInfoFromExprList(pParse, p->pEList, 0),
                                P4_KEYINFO);
    sqlite3VdbeChangeP5(v, BTREE_UNORDERED);
    sDistinct.eTnctType = WHERE_DISTINCT_UNORDERED;
  }else{
    sDistinct.eTnctType = WHERE_DISTINCT_NOOP;
  }

      /* If there is a GROUP BY clause we might need a sorting index to
      ** implement it.  Allocate that sorting index now.  If it turns out
      ** that we do not need it after all, the OP_SorterOpen instruction
      ** will be converted into a Noop.  
      */
      sAggInfo.sortingIdx = pParse->nTab++;
      pKeyInfo = keyInfoFromExprList(pParse, pGroupBy, 0);
      addrSortingIdx = sqlite3VdbeAddOp4(v, OP_SorterOpen, 
          sAggInfo.sortingIdx, sAggInfo.nSortingColumn, 
          0, (char*)pKeyInfo, P4_KEYINFO);

      /* Initialize memory locations used by GROUP BY aggregate processing
      */
      iUseFlag = ++pParse->nMem;

#define SRT_DistQueue   13  /* Like SRT_Queue, but unique results only */

/*
** An instance of this object describes where to put of the results of
** a SELECT statement.
*/
struct SelectDest {
  u8 eDest;            /* How to dispose of the results.  On of SRT_* above. */
  char affSdst;        /* Affinity used when eDest==SRT_Set */
  int iSDParm;         /* A parameter used by the eDest disposal method */
  int iSdst;           /* Base register where results are written */
  int nSdst;           /* Number of registers allocated */
  ExprList *pOrderBy;  /* Key columns for SRT_Queue and SRT_DistQueue */
};

/*
** During code generation of statements that do inserts into AUTOINCREMENT 
** tables, the following information is attached to the Table.u.autoInc.p
** pointer of each autoincrement table to record some side information that
** the code generator needs.  We have to keep per-table autoincrement

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

do_catchsql_test 5.2 {
  WITH i(x) AS ( VALUES(1) UNION ALL SELECT x+1 FROM i ORDER BY 1)
  SELECT x FROM i LIMIT 10;
} {0 {1 2 3 4 5 6 7 8 9 10}}

do_execsql_test 5.2.1 {
  CREATE TABLE edge(xfrom, xto, seq, PRIMARY KEY(xfrom, xto)) WITHOUT ROWID;
  INSERT INTO edge VALUES(0, 1, 10);
  INSERT INTO edge VALUES(1, 2, 20);
  INSERT INTO edge VALUES(0, 3, 30);
  INSERT INTO edge VALUES(2, 4, 40);
  INSERT INTO edge VALUES(3, 4, 40);
  INSERT INTO edge VALUES(2, 5, 50);
  INSERT INTO edge VALUES(3, 6, 60);
  INSERT INTO edge VALUES(5, 7, 70);
  INSERT INTO edge VALUES(3, 7, 70);
  INSERT INTO edge VALUES(4, 8, 80);
  INSERT INTO edge VALUES(7, 8, 80);
  INSERT INTO edge VALUES(8, 9, 90);
  
  WITH RECURSIVE
    ancest(id, mtime) AS
      (VALUES(0, 0)
       UNION
       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 5 50 6 60 7 70 8 80 9 90}
do_execsql_test 5.2.2 {
  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
      )
  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_catchsql_test 5.3 {
  WITH i(x) AS ( VALUES(1) UNION ALL SELECT x+1 FROM i LIMIT 10 )
  SELECT x FROM i LIMIT 10;
} {1 {LIMIT in a recursive query}}

do_execsql_test 5.4 {