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Make subquery aliases optional in the FROM clause.

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This allows aliases for sub-SELECTs and VALUES clauses in the FROM
clause to be omitted.

This is an extension of the SQL standard, supported by some other
database systems, and so eases the transition from such systems, as
well as removing the minor inconvenience caused by requiring these
aliases.

Patch by me, reviewed by Tom Lane.

Discussion: https://postgr.es/m/CAEZATCUCGCf82=hxd9N5n6xGHPyYpQnxW8HneeH+uP7yNALkWA@mail.gmail.com
This commit is contained in:
Dean Rasheed
2022-07-20 09:29:42 +01:00
parent 1caf915ff3
commit bcedd8f5fc
10 changed files with 164 additions and 81 deletions
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19
src/backend/parser/analyze.c
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@@ -3291,7 +3291,7 @@ transformLockingClause(ParseState *pstate, Query *qry, LockingClause *lc,
foreach(rt, qry->rtable)
{
RangeTblEntry *rte = (RangeTblEntry *) lfirst(rt);
char *rtename;
char *rtename = rte->eref->aliasname;
++i;
if (!rte->inFromCl)
@@ -3302,15 +3302,22 @@ transformLockingClause(ParseState *pstate, Query *qry, LockingClause *lc,
* name and needs to be skipped (otherwise it might hide a
* base relation with the same name), except if it has a USING
* alias, which *is* visible.
*
* Subquery and values RTEs without aliases are never visible
* as relation names and must always be skipped.
*/
if (rte->rtekind == RTE_JOIN && rte->alias == NULL)
if (rte->alias == NULL)
{
if (rte->join_using_alias == NULL)
if (rte->rtekind == RTE_JOIN)
{
if (rte->join_using_alias == NULL)
continue;
rtename = rte->join_using_alias->aliasname;
}
else if (rte->rtekind == RTE_SUBQUERY ||
rte->rtekind == RTE_VALUES)
continue;
rtename = rte->join_using_alias->aliasname;
}
else
rtename = rte->eref->aliasname;
if (strcmp(rtename, thisrel->relname) == 0)
{