SQLite

          sNC.pNext = 0;
          pSubNC = pOuterNC;
        }
        sqlite3ResolveSelectNames(pParse, pItem->pSelect, pSubNC);
        p->pSrc->nSrc = nSrc;
        if( sNC.nRef>nRef2 ){
          pItem->fg.isCorrelated = 1;



        }
        pParse->zAuthContext = zSavedContext;
        if( pParse->nErr ) return WRC_Abort;
        assert( db->mallocFailed==0 );

        /* If the number of references to the outer context changed when
        ** expressions in the sub-select were resolved, the sub-select

**                    being used as the outer loop if the sqlite3WhereBegin()
**                    routine nominates it to that position.
**              (iii) The query is not a UPDATE ... FROM
**    (2)  The subquery is not a CTE that should be materialized because
**         (a) the AS MATERIALIZED keyword is used, or
**         (b) the CTE is used multiple times and does not have the
**             NOT MATERIALIZED keyword
**    (3)  The FROM clause does not contain a RIGHT JOIN
**    (4)  The SQLITE_Coroutine optimization disable flag is not set
**    (5)  The subquery is not self-joined
*/
static int fromClauseTermCanBeCoroutine(
  Parse *pParse,          /* Parsing context */
  SrcList *pTabList,      /* FROM clause */
  int i,                  /* Which term of the FROM clause holds the subquery */
  int selFlags            /* Flags on the SELECT statement */
){
  SrcItem *pItem = &pTabList->a[i];
  if( pItem->fg.isCte ){
    const CteUse *pCteUse = pItem->u2.pCteUse;
    if( pCteUse->eM10d==M10d_Yes ) return 0;                          /* (2a) */
    if( pCteUse->nUse>=2 && pCteUse->eM10d!=M10d_No ) return 0;       /* (2b) */
  }
  if( pTabList->a[0].fg.jointype & JT_LTORJ ) return 0;               /* (3)  */


  if( OptimizationDisabled(pParse->db, SQLITE_Coroutines) ) return 0; /* (4)  */
  if( isSelfJoinView(pTabList, pItem, i+1, pTabList->nSrc)!=0 ){
    return 0;                                                          /* (5) */
  }
  if( i==0 ){
    if( pTabList->nSrc==1 ) return 1;                             /* (1a) */
    if( pTabList->a[1].fg.jointype & JT_CROSS ) return 1;         /* (1b) */

        VdbeNoopComment((v, "materialize %!S", pItem));
      }
      sqlite3SelectDestInit(&dest, SRT_EphemTab, pItem->iCursor);

      ExplainQueryPlan2(addrExplain, (pParse, 1, "MATERIALIZE %!S", pItem));
      sqlite3Select(pParse, pSub, &dest);
      pItem->pTab->nRowLogEst = pSub->nSelectRow;
      if( pItem->fg.isLateral && pItem->fg.isCorrelated ){
        int kk;
        for(kk=0; kk<i; kk++){
          SrcItem *pX = &pTabList->a[kk];
          if( pX->fg.viaCoroutine==0 ) continue;
          sqlite3TranslateColumnToCopy(pParse, topAddr+1,
             pX->iCursor, pX->regResult, 0);
        }
      }
      if( onceAddr ) sqlite3VdbeJumpHere(v, onceAddr);
      sqlite3VdbeAddOp2(v, OP_Return, pItem->regReturn, topAddr+1);
      VdbeComment((v, "end %!S", pItem));
      sqlite3VdbeScanStatusRange(v, addrExplain, addrExplain, -1);
      sqlite3VdbeJumpHere(v, topAddr);
      sqlite3ClearTempRegCache(pParse);
      if( pItem->fg.isCte && pItem->fg.isCorrelated==0 ){

void sqlite3CodeChangeCount(Vdbe*,int,const char*);
void sqlite3DeleteFrom(Parse*, SrcList*, Expr*, ExprList*, Expr*);
void sqlite3Update(Parse*, SrcList*, ExprList*,Expr*,int,ExprList*,Expr*,
                   Upsert*);
WhereInfo *sqlite3WhereBegin(Parse*,SrcList*,Expr*,ExprList*,
                             ExprList*,Select*,u16,int);
void sqlite3WhereEnd(WhereInfo*);
void sqlite3TranslateColumnToCopy(
  Parse *pParse,      /* Parsing context */
  int iStart,         /* Translate from this opcode to the end */
  int iTabCur,        /* OP_Column/OP_Rowid references to this table */
  int iRegister,      /* The first column is in this register */
  int iAutoidxCur     /* If non-zero, cursor of autoindex being generated */
);
LogEst sqlite3WhereOutputRowCount(WhereInfo*);
int sqlite3WhereIsDistinct(WhereInfo*);
int sqlite3WhereIsOrdered(WhereInfo*);
int sqlite3WhereOrderByLimitOptLabel(WhereInfo*);
void sqlite3WhereMinMaxOptEarlyOut(Vdbe*,WhereInfo*);
int sqlite3WhereIsSorted(WhereInfo*);
int sqlite3WhereContinueLabel(WhereInfo*);

** instead of via table lookup.
**
** If the iAutoidxCur is not zero, then any OP_Rowid instructions on
** cursor iTabCur are transformed into OP_Sequence opcode for the
** iAutoidxCur cursor, in order to generate unique rowids for the
** automatic index being generated.
*/
void sqlite3TranslateColumnToCopy(
  Parse *pParse,      /* Parsing context */
  int iStart,         /* Translate from this opcode to the end */
  int iTabCur,        /* OP_Column/OP_Rowid references to this table */
  int iRegister,      /* The first column is in this register */
  int iAutoidxCur     /* If non-zero, cursor of autoindex being generated */
){
  Vdbe *v = pParse->pVdbe;

  sqlite3VdbeAddOp2(v, OP_IdxInsert, pLevel->iIdxCur, regRecord);
  sqlite3VdbeChangeP5(v, OPFLAG_USESEEKRESULT);
  if( pPartial ) sqlite3VdbeResolveLabel(v, iContinue);
  if( pSrc->fg.viaCoroutine ){
    sqlite3VdbeChangeP2(v, addrCounter, regBase+n);
    testcase( pParse->db->mallocFailed );
    assert( pLevel->iIdxCur>0 );
    sqlite3TranslateColumnToCopy(pParse, addrTop, pLevel->iTabCur,
                                 pSrc->regResult, pLevel->iIdxCur);
    sqlite3VdbeGoto(v, addrTop);
    pSrc->fg.viaCoroutine = 0;
  }else{
    sqlite3VdbeAddOp2(v, OP_Next, pLevel->iTabCur, addrTop+1); VdbeCoverage(v);
    sqlite3VdbeChangeP5(v, SQLITE_STMTSTATUS_AUTOINDEX);
  }
  sqlite3VdbeJumpHere(v, addrTop);

    /* For a co-routine, change all OP_Column references to the table of
    ** the co-routine into OP_Copy of result contained in a register.
    ** OP_Rowid becomes OP_Null.
    */
    if( pTabItem->fg.viaCoroutine ){
      testcase( pParse->db->mallocFailed );
      assert( pTabItem->regResult>=0 );
      sqlite3TranslateColumnToCopy(pParse, pLevel->addrBody, pLevel->iTabCur,
                                   pTabItem->regResult, 0);
      continue;
    }

    /* If this scan uses an index, make VDBE code substitutions to read data
    ** from the index instead of from the table where possible.  In some cases
    ** this optimization prevents the table from ever being read, which can
    ** yield a significant performance boost.

  INSERT INTO lateral VALUES(1,2);
  SELECT * FROM lateral;
  ATTACH ':memory:' AS lateral;
  CREATE TABLE lateral.t2(x,y);
  INSERT INTO t2 VALUES(98,99);
  SELECT * FROM t2;
} {1 2 98 99}

# https://sqlite.org/forum/forumpost/dfe2cd37ca3a9a80
#
do_execsql_test 4.0 {
  SELECT * FROM (VALUES (1), (2)) JOIN LATERAL (select COUNT(*), column1);
} {1 1 1 2 1 2}

finish_test