SQLite

    pNew->addrOpenEphm[1] = -1;
    pNew->nSelectRow = p->nSelectRow;
    pNew->pWith = withDup(db, p->pWith);
#ifndef SQLITE_OMIT_WINDOWFUNC
    pNew->pWin = 0;
    pNew->pWinDefn = sqlite3WindowListDup(db, p->pWinDefn);
#endif
    sqlite3SelectSetName(pNew, p->zSelName);
    *pp = pNew;
    pp = &pNew->pPrior;
    pNext = pNew;
  }

  return pRet;
}

  A = pRhs;
}
%type multiselect_op {int}
multiselect_op(A) ::= UNION(OP).             {A = @OP; /*A-overwrites-OP*/}
multiselect_op(A) ::= UNION ALL.             {A = TK_ALL;}
multiselect_op(A) ::= EXCEPT|INTERSECT(OP).  {A = @OP; /*A-overwrites-OP*/}
%endif SQLITE_OMIT_COMPOUND_SELECT
oneselect(A) ::= SELECT(S) distinct(D) selcollist(W) from(X) where_opt(Y)
                 groupby_opt(P) having_opt(Q) 
%ifndef SQLITE_OMIT_WINDOWFUNC
                 windowdefn_opt(R)
%endif
                 orderby_opt(Z) limit_opt(L). {
#if SELECTTRACE_ENABLED
  Token s = S; /*A-overwrites-S*/
#endif
  A = sqlite3SelectNew(pParse,W,X,Y,P,Q,Z,D,L);
#ifndef SQLITE_OMIT_WINDOWFUNC
  if( A ){
    A->pWinDefn = R;
  }else{
    sqlite3WindowListDelete(pParse->db, R);
  }
#endif /* SQLITE_OMIT_WINDOWFUNC */
#if SELECTTRACE_ENABLED
  /* Populate the Select.zSelName[] string that is used to help with
  ** query planner debugging, to differentiate between multiple Select
  ** objects in a complex query.
  **
  ** If the SELECT keyword is immediately followed by a C-style comment
  ** then extract the first few alphanumeric characters from within that
  ** comment to be the zSelName value.  Otherwise, the label is #N where
  ** is an integer that is incremented with each SELECT statement seen.
  */
  if( A!=0 ){
    const char *z = s.z+6;
    int i;
    sqlite3_snprintf(sizeof(A->zSelName), A->zSelName,"#%d",++pParse->nSelect);
    while( z[0]==' ' ) z++;
    if( z[0]=='/' && z[1]=='*' ){
      z += 2;
      while( z[0]==' ' ) z++;
      for(i=0; sqlite3Isalnum(z[i]); i++){}
      sqlite3_snprintf(sizeof(A->zSelName), A->zSelName, "%.*s", i, z);
    }
  }
#endif /* SELECTRACE_ENABLED */
}
oneselect(A) ::= values(A).

%type values {Select*}
%destructor values {sqlite3SelectDelete(pParse->db, $$);}
values(A) ::= VALUES LP nexprlist(X) RP. {
  A = sqlite3SelectNew(pParse,X,0,0,0,0,0,SF_Values,0);

/*
** Trace output macros
*/
#if SELECTTRACE_ENABLED
/***/ int sqlite3SelectTrace = 0;
# define SELECTTRACE(K,P,S,X)  \
  if(sqlite3SelectTrace&(K))   \
    sqlite3DebugPrintf("%s/%d/%p: ",(S)->zSelName,(P)->addrExplain,(S)),\
    sqlite3DebugPrintf X
#else
# define SELECTTRACE(K,P,S,X)
#endif


/*

                                   sqlite3Expr(pParse->db,TK_ASTERISK,0));
  }
  pNew->pEList = pEList;
  pNew->op = TK_SELECT;
  pNew->selFlags = selFlags;
  pNew->iLimit = 0;
  pNew->iOffset = 0;
#if SELECTTRACE_ENABLED
  pNew->zSelName[0] = 0;
#endif
  pNew->addrOpenEphm[0] = -1;
  pNew->addrOpenEphm[1] = -1;
  pNew->nSelectRow = 0;
  if( pSrc==0 ) pSrc = sqlite3DbMallocZero(pParse->db, sizeof(*pSrc));
  pNew->pSrc = pSrc;
  pNew->pWhere = pWhere;
  pNew->pGroupBy = pGroupBy;

  }else{
    assert( pNew->pSrc!=0 || pParse->nErr>0 );
  }
  assert( pNew!=&standin );
  return pNew;
}

#if SELECTTRACE_ENABLED
/*
** Set the name of a Select object
*/
void sqlite3SelectSetName(Select *p, const char *zName){
  if( p && zName ){
    sqlite3_snprintf(sizeof(p->zSelName), p->zSelName, "%s", zName);
  }
}
#endif


/*
** Delete the given Select structure and all of its substructures.
*/
void sqlite3SelectDelete(sqlite3 *db, Select *p){
  if( OK_IF_ALWAYS_TRUE(p) ) clearSelect(db, p, 1);
}

  ** subquery is for the subquery to be one term of a join.  But if the
  ** subquery is a join, then the flattening has already been stopped by
  ** restriction (17d3)
  */
  assert( (p->selFlags & SF_Recursive)==0 || pSub->pPrior==0 );

  /***** If we reach this point, flattening is permitted. *****/
  SELECTTRACE(1,pParse,p,("flatten %s.%p from term %d\n",
                   pSub->zSelName, pSub, iFrom));

  /* Authorize the subquery */
  pParse->zAuthContext = pSubitem->zName;
  TESTONLY(i =) sqlite3AuthCheck(pParse, SQLITE_SELECT, 0, 0, 0);
  testcase( i==SQLITE_DENY );
  pParse->zAuthContext = zSavedAuthContext;

    Expr *pLimit = p->pLimit;
    Select *pPrior = p->pPrior;
    p->pOrderBy = 0;
    p->pSrc = 0;
    p->pPrior = 0;
    p->pLimit = 0;
    pNew = sqlite3SelectDup(db, p, 0);
    sqlite3SelectSetName(pNew, pSub->zSelName);
    p->pLimit = pLimit;
    p->pOrderBy = pOrderBy;
    p->pSrc = pSrc;
    p->op = TK_ALL;
    if( pNew==0 ){
      p->pPrior = pPrior;
    }else{
      pNew->pPrior = pPrior;
      if( pPrior ) pPrior->pNext = pNew;
      pNew->pNext = p;
      p->pPrior = pNew;
      SELECTTRACE(2,pParse,p,("compound-subquery flattener"
                              " creates %s.%p as peer\n",pNew->zSelName, pNew));
    }
    if( db->mallocFailed ) return 1;
  }

  /* Begin flattening the iFrom-th entry of the FROM clause 
  ** in the outer query.
  */

  assert( pSel );
  pFrom->pTab = pTab = sqlite3DbMallocZero(pParse->db, sizeof(Table));
  if( pTab==0 ) return SQLITE_NOMEM;
  pTab->nTabRef = 1;
  if( pFrom->zAlias ){
    pTab->zName = sqlite3DbStrDup(pParse->db, pFrom->zAlias);
  }else{
    pTab->zName = sqlite3MPrintf(pParse->db, "subquery_%p", (void*)pTab);
  }
  while( pSel->pPrior ){ pSel = pSel->pPrior; }
  sqlite3ColumnsFromExprList(pParse, pSel->pEList,&pTab->nCol,&pTab->aCol);
  pTab->iPKey = -1;
  pTab->nRowLogEst = 200; assert( 200==sqlite3LogEst(1048576) );
  pTab->tabFlags |= TF_Ephemeral;

      }
#if !defined(SQLITE_OMIT_VIEW) || !defined (SQLITE_OMIT_VIRTUALTABLE)
      if( IsVirtual(pTab) || pTab->pSelect ){
        i16 nCol;
        if( sqlite3ViewGetColumnNames(pParse, pTab) ) return WRC_Abort;
        assert( pFrom->pSelect==0 );
        pFrom->pSelect = sqlite3SelectDup(db, pTab->pSelect, 0);
        sqlite3SelectSetName(pFrom->pSelect, pTab->zName);
        nCol = pTab->nCol;
        pTab->nCol = -1;
        sqlite3WalkSelect(pWalker, pFrom->pSelect);
        pTab->nCol = nCol;
      }
#endif
    }

      int addrTop = sqlite3VdbeCurrentAddr(v)+1;
     
      pItem->regReturn = ++pParse->nMem;
      sqlite3VdbeAddOp3(v, OP_InitCoroutine, pItem->regReturn, 0, addrTop);
      VdbeComment((v, "%s", pItem->pTab->zName));
      pItem->addrFillSub = addrTop;
      sqlite3SelectDestInit(&dest, SRT_Coroutine, pItem->regReturn);
      ExplainQueryPlan((pParse, 1, "CO-ROUTINE 0x%p", pSub));
      sqlite3Select(pParse, pSub, &dest);
      pItem->pTab->nRowLogEst = pSub->nSelectRow;
      pItem->fg.viaCoroutine = 1;
      pItem->regResult = dest.iSdst;
      sqlite3VdbeEndCoroutine(v, pItem->regReturn);
      sqlite3VdbeJumpHere(v, addrTop-1);
      sqlite3ClearTempRegCache(pParse);

      pPrior = isSelfJoinView(pTabList, pItem);
      if( pPrior ){
        sqlite3VdbeAddOp2(v, OP_OpenDup, pItem->iCursor, pPrior->iCursor);
        assert( pPrior->pSelect!=0 );
        pSub->nSelectRow = pPrior->pSelect->nSelectRow;
      }else{
        sqlite3SelectDestInit(&dest, SRT_EphemTab, pItem->iCursor);
        ExplainQueryPlan((pParse, 1, "MATERIALIZE 0x%p", pSub));
        sqlite3Select(pParse, pSub, &dest);
      }
      pItem->pTab->nRowLogEst = pSub->nSelectRow;
      if( onceAddr ) sqlite3VdbeJumpHere(v, onceAddr);
      retAddr = sqlite3VdbeAddOp1(v, OP_Return, pItem->regReturn);
      VdbeComment((v, "end %s", pItem->pTab->zName));
      sqlite3VdbeChangeP1(v, topAddr, retAddr);

*/
struct Select {
  ExprList *pEList;      /* The fields of the result */
  u8 op;                 /* One of: TK_UNION TK_ALL TK_INTERSECT TK_EXCEPT */
  LogEst nSelectRow;     /* Estimated number of result rows */
  u32 selFlags;          /* Various SF_* values */
  int iLimit, iOffset;   /* Memory registers holding LIMIT & OFFSET counters */
#if SELECTTRACE_ENABLED
  char zSelName[12];     /* Symbolic name of this SELECT use for debugging */
#endif
  int addrOpenEphm[2];   /* OP_OpenEphem opcodes related to this select */
  SrcList *pSrc;         /* The FROM clause */
  Expr *pWhere;          /* The WHERE clause */
  ExprList *pGroupBy;    /* The GROUP BY clause */
  Expr *pHaving;         /* The HAVING clause */
  ExprList *pOrderBy;    /* The ORDER BY clause */
  Select *pPrior;        /* Prior select in a compound select statement */

  ExprList *pConstExpr;/* Constant expressions */
  Token constraintName;/* Name of the constraint currently being parsed */
  yDbMask writeMask;   /* Start a write transaction on these databases */
  yDbMask cookieMask;  /* Bitmask of schema verified databases */
  int regRowid;        /* Register holding rowid of CREATE TABLE entry */
  int regRoot;         /* Register holding root page number for new objects */
  int nMaxArg;         /* Max args passed to user function by sub-program */
#if SELECTTRACE_ENABLED
  int nSelect;         /* Number of SELECT statements seen */
#endif
#ifndef SQLITE_OMIT_SHARED_CACHE
  int nTableLock;        /* Number of locks in aTableLock */
  TableLock *aTableLock; /* Required table locks for shared-cache mode */
#endif
  AutoincInfo *pAinc;  /* Information about AUTOINCREMENT counters */
  Parse *pToplevel;    /* Parse structure for main program (or NULL) */
  Table *pTriggerTab;  /* Table triggers are being coded for */

void sqlite3UniqueConstraint(Parse*, int, Index*);
void sqlite3RowidConstraint(Parse*, int, Table*);
Expr *sqlite3ExprDup(sqlite3*,Expr*,int);
ExprList *sqlite3ExprListDup(sqlite3*,ExprList*,int);
SrcList *sqlite3SrcListDup(sqlite3*,SrcList*,int);
IdList *sqlite3IdListDup(sqlite3*,IdList*);
Select *sqlite3SelectDup(sqlite3*,Select*,int);
#if SELECTTRACE_ENABLED
void sqlite3SelectSetName(Select*,const char*);
#else
# define sqlite3SelectSetName(A,B)
#endif
void sqlite3InsertBuiltinFuncs(FuncDef*,int);
FuncDef *sqlite3FindFunction(sqlite3*,const char*,int,u8,u8);
void sqlite3RegisterBuiltinFunctions(void);
void sqlite3RegisterDateTimeFunctions(void);
void sqlite3RegisterPerConnectionBuiltinFunctions(sqlite3*);
int sqlite3SafetyCheckOk(sqlite3*);
int sqlite3SafetyCheckSickOrOk(sqlite3*);

  pView = sqlite3TreeViewPush(pView, moreToFollow);
  if( p->pWith ){
    sqlite3TreeViewWith(pView, p->pWith, 1);
    cnt = 1;
    sqlite3TreeViewPush(pView, 1);
  }
  do{
#if SELECTTRACE_ENABLED
    sqlite3TreeViewLine(pView,
      "SELECT%s%s (%s/%p) selFlags=0x%x nSelectRow=%d",
      ((p->selFlags & SF_Distinct) ? " DISTINCT" : ""),
      ((p->selFlags & SF_Aggregate) ? " agg_flag" : ""),
      p->zSelName, p, p->selFlags,
      (int)p->nSelectRow
    );
#else
    sqlite3TreeViewLine(pView, "SELECT%s%s (0x%p) selFlags=0x%x nSelectRow=%d",
      ((p->selFlags & SF_Distinct) ? " DISTINCT" : ""),
      ((p->selFlags & SF_Aggregate) ? " agg_flag" : ""), p, p->selFlags,
      (int)p->nSelectRow
    );
#endif
    if( cnt++ ) sqlite3TreeViewPop(pView);
    if( p->pPrior ){
      n = 1000;
    }else{
      n = 0;
      if( p->pSrc && p->pSrc->nSrc ) n++;
      if( p->pWhere ) n++;

  pTabItem = &pWC->pWInfo->pTabList->a[pLevel->iFrom];
  if( pTabItem->fg.viaCoroutine ){
    int regYield = pTabItem->regReturn;
    addrCounter = sqlite3VdbeAddOp2(v, OP_Integer, 0, 0);
    sqlite3VdbeAddOp3(v, OP_InitCoroutine, regYield, 0, pTabItem->addrFillSub);
    addrTop =  sqlite3VdbeAddOp1(v, OP_Yield, regYield);
    VdbeCoverage(v);
    VdbeComment((v, "next row of \"%s\"", pTabItem->pTab->zName));
  }else{
    addrTop = sqlite3VdbeAddOp1(v, OP_Rewind, pLevel->iTabCur); VdbeCoverage(v);
  }
  if( pPartial ){
    iContinue = sqlite3VdbeMakeLabel(v);
    sqlite3ExprIfFalse(pParse, pPartial, iContinue, SQLITE_JUMPIFNULL);
    pLoop->wsFlags |= WHERE_PARTIALIDX;

    isSearch = (flags&(WHERE_BTM_LIMIT|WHERE_TOP_LIMIT))!=0
            || ((flags&WHERE_VIRTUALTABLE)==0 && (pLoop->u.btree.nEq>0))
            || (wctrlFlags&(WHERE_ORDERBY_MIN|WHERE_ORDERBY_MAX));

    sqlite3StrAccumInit(&str, db, zBuf, sizeof(zBuf), SQLITE_MAX_LENGTH);
    sqlite3_str_appendall(&str, isSearch ? "SEARCH" : "SCAN");
    if( pItem->pSelect ){
      sqlite3_str_appendf(&str, " SUBQUERY 0x%p", pItem->pSelect);
    }else{
      sqlite3_str_appendf(&str, " TABLE %s", pItem->zName);
    }

    if( pItem->zAlias ){
      sqlite3_str_appendf(&str, " AS %s", pItem->zAlias);
    }

  /* Special case of a FROM clause subquery implemented as a co-routine */
  if( pTabItem->fg.viaCoroutine ){
    int regYield = pTabItem->regReturn;
    sqlite3VdbeAddOp3(v, OP_InitCoroutine, regYield, 0, pTabItem->addrFillSub);
    pLevel->p2 =  sqlite3VdbeAddOp2(v, OP_Yield, regYield, addrBrk);
    VdbeCoverage(v);
    VdbeComment((v, "next row of \"%s\"", pTabItem->pTab->zName));
    pLevel->op = OP_Goto;
  }else

#ifndef SQLITE_OMIT_VIRTUALTABLE
  if(  (pLoop->wsFlags & WHERE_VIRTUALTABLE)!=0 ){
    /* Case 1:  The table is a virtual-table.  Use the VFilter and VNext
    **          to access the data.

  SELECT * 
   FROM t41
   LEFT JOIN (SELECT count(*) AS cnt, x1.d
                FROM (t42 INNER JOIN t43 ON d=g) AS x1
               WHERE x1.d>5
               GROUP BY x1.d) AS x2
                  ON t41.b=x2.d;
} {/*SEARCH SUBQUERY 0x* AS x2 USING AUTOMATIC*/}

finish_test

proc query_plan_graph {sql} {
  db eval "EXPLAIN QUERY PLAN $sql" {
    set dx($id) $detail
    lappend cx($parent) $id
  }
  set a "\n  QUERY PLAN\n"
  append a [append_graph "  " dx cx 0]
  return [regsub -all { 0x[A-F0-9]+\y} $a { xxxxxx}]


}

# Helper routine for [query_plan_graph SQL]:
#
# Output rows of the graph that are children of $level.
#
#   prefix:  Prepend to every output line