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Implement subselects in target lists. Also, relax requirement that

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subselects can only appear on the righthand side of a binary operator.
That's still true for quantified predicates like x = ANY (SELECT ...),
but a subselect that delivers a single result can now appear anywhere
in an expression.  This is implemented by changing EXPR_SUBLINK sublinks
to represent just the (SELECT ...) expression, without any 'left hand
side' or combining operator --- so they're now more like EXISTS_SUBLINK.
To handle the case of '(x, y, z) = (SELECT ...)', I added a new sublink
type MULTIEXPR_SUBLINK, which acts just like EXPR_SUBLINK used to.
But the grammar will only generate one for a multiple-left-hand-side
row expression.
This commit is contained in:
Tom Lane
1999-11-15 02:00:15 +00:00
parent 1ecb129d20
commit f68e11f373
12 changed files with 364 additions and 566 deletions
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30
src/backend/utils/adt/ruleutils.c
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@ -3,7 +3,7 @@
* out of it's tuple
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/utils/adt/ruleutils.c,v 1.30 1999/11/07 23:08:24 momjian Exp $
* $Header: /cvsroot/pgsql/src/backend/utils/adt/ruleutils.c,v 1.31 1999/11/15 02:00:05 tgl Exp $
*
* This software is copyrighted by Jan Wieck - Hamburg.
*
@ -1681,15 +1681,17 @@ get_sublink_expr(Node *node, deparse_context *context)
StringInfo buf = context->buf;
SubLink *sublink = (SubLink *) node;
Query *query = (Query *) (sublink->subselect);
Oper *oper;
List *l;
char *sep;
Oper *oper;
bool need_paren;
appendStringInfo(buf, "(");
if (sublink->lefthand != NULL)
if (sublink->lefthand != NIL)
{
if (length(sublink->lefthand) > 1)
need_paren = (length(sublink->lefthand) > 1);
if (need_paren)
appendStringInfo(buf, "(");
sep = "";
@ -1700,12 +1702,14 @@ get_sublink_expr(Node *node, deparse_context *context)
get_rule_expr((Node *) lfirst(l), context);
}
if (length(sublink->lefthand) > 1)
if (need_paren)
appendStringInfo(buf, ") ");
else
appendStringInfo(buf, " ");
}
need_paren = true;
switch (sublink->subLinkType)
{
case EXISTS_SUBLINK:
@ -1722,20 +1726,30 @@ get_sublink_expr(Node *node, deparse_context *context)
appendStringInfo(buf, "%s ALL ", get_opname(oper->opno));
break;
case EXPR_SUBLINK:
case MULTIEXPR_SUBLINK:
oper = (Oper *) lfirst(sublink->oper);
appendStringInfo(buf, "%s ", get_opname(oper->opno));
break;
case EXPR_SUBLINK:
need_paren = false;
break;
default:
elog(ERROR, "get_sublink_expr: unsupported sublink type %d",
sublink->subLinkType);
break;
}
appendStringInfo(buf, "(");
if (need_paren)
appendStringInfo(buf, "(");
get_query_def(query, buf, context->rangetables);
appendStringInfo(buf, "))");
if (need_paren)
appendStringInfo(buf, "))");
else
appendStringInfo(buf, ")");
}
/* ----------