SQLite

      for(i=0, pItem=pSrcList->a; i<pSrcList->nSrc; i++, pItem++){
        Table *pTab;
        Column *pCol;
  
        pTab = pItem->pTab;
        assert( pTab!=0 && pTab->zName!=0 );
        assert( pTab->nCol>0 );
        if( zDb && pTab->pSchema!=pSchema ){
          continue;
        }
        if( pItem->pSelect && (pItem->pSelect->selFlags & SF_NestedFrom)!=0 ){
          ExprList *pEList = pItem->pSelect->pEList;
          int hit = 0;
          for(j=0; j<pEList->nExpr; j++){
            if( sqlite3MatchSpanName(pEList->a[j].zSpan, zCol, zTab, zDb) ){
              cnt++;
              cntTab = 2;
              pMatch = pItem;
              pExpr->iColumn = j;
            }
          }
          if( hit || zTab==0 ) continue;
        }
        if( zDb && pTab->pSchema!=pSchema ){
          continue;
        }
        if( zTab ){
          const char *zTabName = pItem->zAlias ? pItem->zAlias : pTab->zName;
          assert( zTabName!=0 );
          if( sqlite3StrICmp(zTabName, zTab)!=0 ){
            continue;
          }

  *pnCol = nCol;
  *paCol = aCol;

  for(i=0, pCol=aCol; i<nCol; i++, pCol++){
    /* Get an appropriate name for the column
    */
    p = sqlite3ExprSkipCollate(pEList->a[i].pExpr);
    assert( p->pRight==0 || ExprHasProperty(p->pRight, EP_IntValue)
               || p->pRight->u.zToken==0 || p->pRight->u.zToken[0]!=0 );
    if( (zName = pEList->a[i].zName)!=0 ){
      /* If the column contains an "AS <name>" phrase, use <name> as the name */
      zName = sqlite3DbStrDup(db, zName);
    }else{
      Expr *pColExpr = p;  /* The expression that is the result column name */
      Table *pTab;         /* Table associated with this expression */
      while( pColExpr->op==TK_DOT ){

          zTName = pE->pLeft->u.zToken;
        }
        for(i=0, pFrom=pTabList->a; i<pTabList->nSrc; i++, pFrom++){
          Table *pTab = pFrom->pTab;
          Select *pSub = pFrom->pSelect;
          char *zTabName = pFrom->zAlias;
          const char *zSchemaName = 0;
          int iDb;
          if( zTabName==0 ){
            zTabName = pTab->zName;
          }
          if( db->mallocFailed ) break;
          if( pSub==0 || (pSub->selFlags & SF_NestedFrom)==0 ){
            int iDb;
            pSub = 0;
            if( zTName && sqlite3StrICmp(zTName, zTabName)!=0 ){
              continue;
            }
            iDb = sqlite3SchemaToIndex(db, pTab->pSchema);
            zSchemaName = iDb>=0 ? db->aDb[i].zName : "*";
            zSchemaName = iDb>=0 ? db->aDb[iDb].zName : "*";
          }
          for(j=0; j<pTab->nCol; j++){
            char *zName = pTab->aCol[j].zName;
            char *zColname;  /* The computed column name */
            char *zToFree;   /* Malloced string that needs to be freed */
            Token sColname;  /* Computed column name as a token */

            assert( zName );
            if( zTName && pSub
             && sqlite3MatchSpanName(pSub->pEList->a[j].zSpan, 0, zTName, 0)==0
            ){
              continue;
            }

            /* If a column is marked as 'hidden' (currently only possible

            pRight = sqlite3Expr(db, TK_ID, zName);
            zColname = zName;
            zToFree = 0;
            if( longNames || pTabList->nSrc>1 ){
              Expr *pLeft;
              pLeft = sqlite3Expr(db, TK_ID, zTabName);
              pExpr = sqlite3PExpr(pParse, TK_DOT, pLeft, pRight, 0);
              if( zSchemaName && iDb>0 ){
                pLeft = sqlite3Expr(db, TK_ID, zSchemaName);
                pExpr = sqlite3PExpr(pParse, TK_DOT, pLeft, pExpr, 0);
              }
              if( longNames ){
                zColname = sqlite3MPrintf(db, "%s.%s", zTabName, zName);
                zToFree = zColname;
              }
            }else{
              pExpr = pRight;
            }
            pNew = sqlite3ExprListAppend(pParse, pNew, pExpr);
            sColname.z = zColname;
            sColname.n = sqlite3Strlen30(zColname);
            sqlite3ExprListSetName(pParse, pNew, &sColname, 0);
            if( pNew && (p->selFlags & SF_NestedFrom)!=0 ){
              struct ExprList_item *pX = &pNew->a[pNew->nExpr-1];
              if( pSub ){
                pX->zSpan = sqlite3DbStrDup(db, pSub->pEList->a[j].zSpan);
                testcase( pX->zSpan==0 );
              }else{
                pX->zSpan = sqlite3MPrintf(db, "%s.%s.%s",
                                           zSchemaName, zTabName, zColname);
                testcase( pX->zSpan==0 );
              }
              pX->bSpanIsTab = 1;
            }
            sqlite3DbFree(db, zToFree);
          }
        }
        if( !tableSeen ){

  forcedelete test$i.db
  sqlite3 db test$i.db
  if {$i==2} {
    optimization_control db query-flattener off
  }
  do_test selectD-$i.0 {
    db eval {
      ATTACH ':memory:' AS aux1;
      CREATE TABLE t1(a,b); INSERT INTO t1 VALUES(111,'x1');
      CREATE TABLE t2(a,b); INSERT INTO t2 VALUES(222,'x2');
      CREATE TEMP TABLE t3(a,b); INSERT INTO t3 VALUES(333,'x3');
      CREATE TABLE t4(a,b); INSERT INTO t4 VALUES(444,'x4');
      CREATE TABLE main.t4(a,b); INSERT INTO main.t4 VALUES(444,'x4');
      CREATE TABLE aux1.t4(a,b); INSERT INTO aux1.t4 VALUES(555,'x5');
    }
  } {}
  do_test selectD-$i.1 {
    db eval {
      SELECT *
        FROM (t1), (t2), (t3), (t4)
       WHERE t4.a=t3.a+111 

    db eval {
      SELECT t3.*, t2.*
        FROM t1 JOIN (t2 JOIN (t3 JOIN t4 ON t4.a=t3.a+111)
                              ON t3.a=t2.a+111)
                     ON t2.a=t1.a+111;
    }
  } {333 x3 222 x2}
  do_test selectD-$i.2.4 {
    db eval {
      SELECT *
        FROM t1 JOIN (t2 JOIN (main.t4 JOIN aux1.t4 ON aux1.t4.a=main.t4.a+111)
                              ON main.t4.a=t2.a+222)
                     ON t2.a=t1.a+111;
    }
  } {111 x1 222 x2 444 x4 555 x5}
  do_test selectD-$i.2.5 {
    db eval {
      SELECT *
        FROM t1 JOIN (t2 JOIN (main.t4 AS x JOIN aux1.t4 ON aux1.t4.a=x.a+111)
                              ON x.a=t2.a+222)
                     ON t2.a=t1.a+111;
    }
  } {111 x1 222 x2 444 x4 555 x5}
  do_test selectD-$i.2.6 {
    catchsql {
      SELECT *
        FROM t1 JOIN (t2 JOIN (main.t4 JOIN aux.t4 ON aux.t4.a=main.t4.a+111)
                              ON main.t4.a=t2.a+222)
                     ON t2.a=t1.a+111;
    }
  } {1 {no such table: aux.t4}}
  do_test selectD-$i.2.7 {
    db eval {
      SELECT x.a, y.b
        FROM t1 JOIN (t2 JOIN (main.t4 x JOIN aux1.t4 y ON y.a=x.a+111)
                              ON x.a=t2.a+222)
                     ON t2.a=t1.a+111;
    }
  } {444 x5}
  do_test selectD-$i.3 {
    db eval {
      UPDATE t2 SET a=111;
      UPDATE t3 SET a=111;
      UPDATE t4 SET a=111;
      SELECT *
        FROM t1 JOIN (t2 JOIN (t3 JOIN t4 USING(a)) USING (a)) USING (a);