diff options
Diffstat (limited to 'src/backend/parser/parse_clause.c')
| -rw-r--r-- | src/backend/parser/parse_clause.c | 25 |
1 files changed, 17 insertions, 8 deletions
diff --git a/src/backend/parser/parse_clause.c b/src/backend/parser/parse_clause.c index a6549015af9..68da571f922 100644 --- a/src/backend/parser/parse_clause.c +++ b/src/backend/parser/parse_clause.c @@ -8,7 +8,7 @@ * * * IDENTIFICATION - * $Header: /cvsroot/pgsql/src/backend/parser/parse_clause.c,v 1.54 2000/02/15 23:09:08 tgl Exp $ + * $Header: /cvsroot/pgsql/src/backend/parser/parse_clause.c,v 1.55 2000/02/19 23:45:05 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -721,7 +721,7 @@ parseFromClause(ParseState *pstate, List *frmList) * node the ORDER BY, GROUP BY, or DISTINCT ON expression to be matched * tlist the existing target list (NB: this cannot be NIL, which is a * good thing since we'd be unable to append to it...) - * clause identifies clause type for error messages. + * clause identifies clause type (mainly for error messages). */ static TargetEntry * findTargetlistEntry(ParseState *pstate, Node *node, List *tlist, int clause) @@ -733,7 +733,7 @@ findTargetlistEntry(ParseState *pstate, Node *node, List *tlist, int clause) /*---------- * Handle two special cases as mandated by the SQL92 spec: * - * 1. ORDER/GROUP BY ColumnName + * 1. ORDER BY ColumnName * For a bare identifier, we search for a matching column name * in the existing target list. Multiple matches are an error * unless they refer to identical values; for example, @@ -741,17 +741,26 @@ findTargetlistEntry(ParseState *pstate, Node *node, List *tlist, int clause) * but not SELECT a AS b, b FROM table ORDER BY b * If no match is found, we fall through and treat the identifier * as an expression. + * We do NOT attempt this match for GROUP BY, since it is clearly + * contrary to the spec to use an output column name in preference + * to an underlying column name in GROUP BY. DISTINCT ON isn't in + * the standard, so we can do what we like there; we choose to make + * it work like GROUP BY. * - * 2. ORDER/GROUP BY IntegerConstant + * 2. ORDER BY/GROUP BY/DISTINCT ON IntegerConstant * This means to use the n'th item in the existing target list. - * Note that it would make no sense to order/group by an actual - * constant, so this does not create a conflict with our extension - * to order/group by an expression. + * Note that it would make no sense to order/group/distinct by an + * actual constant, so this does not create a conflict with our + * extension to order/group by an expression. + * I believe that GROUP BY column-number is not sanctioned by SQL92, + * but since the standard has no other behavior defined for this + * syntax, we may as well continue to support our past behavior. * * Note that pre-existing resjunk targets must not be used in either case. *---------- */ - if (IsA(node, Ident) && ((Ident *) node)->indirection == NIL) + if (clause == ORDER_CLAUSE && + IsA(node, Ident) && ((Ident *) node)->indirection == NIL) { char *name = ((Ident *) node)->name; foreach(tl, tlist) |