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Give a good error message for what's likely to be a common syntax error,

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namely omitting the alias clause for a sub-SELECT in FROM.
This commit is contained in:
Tom Lane 2001-01-20 17:37:52 +00:00
parent e832ae337d
commit 1a02edae60
1 changed files with 18 additions and 5 deletions
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23
src/backend/parser/gram.y
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@ -11,7 +11,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/parser/gram.y,v 2.216 2001/01/17 17:26:45 momjian Exp $
* $Header: /cvsroot/pgsql/src/backend/parser/gram.y,v 2.217 2001/01/20 17:37:52 tgl Exp $
*
* HISTORY
* AUTHOR DATE MAJOR EVENT
@ -3604,10 +3604,6 @@ from_list: from_list ',' table_ref { $$ = lappend($1, $3); }
* between table_ref := '(' joined_table ')' alias_clause
* and joined_table := '(' joined_table ')'. So, we must have the
* redundant-looking productions here instead.
*
* Note that the SQL spec does not permit a subselect (<derived_table>)
* without an alias clause, so we don't either. This avoids the problem
* of needing to invent a refname for an unlabeled subselect.
*/
table_ref: relation_expr
{
@ -3618,6 +3614,23 @@ table_ref: relation_expr
$1->name = $2;
$$ = (Node *) $1;
}
| select_with_parens
{
/*
* The SQL spec does not permit a subselect
* (<derived_table>) without an alias clause,
* so we don't either. This avoids the problem
* of needing to invent a unique refname for it.
* That could be surmounted if there's sufficient
* popular demand, but for now let's just implement
* the spec and see if anyone complains.
* However, it does seem like a good idea to emit
* an error message that's better than "parse error".
*/
elog(ERROR, "sub-SELECT in FROM must have an alias"
"\n\tFor example, FROM (SELECT ...) [AS] foo");
$$ = NULL;
}
| select_with_parens alias_clause
{
RangeSubselect *n = makeNode(RangeSubselect);