database/postgres
1
0
Fork 0
mirror of https://github.com/postgres/postgres.git synced 2025-06-14 18:42:34 +03:00
Code Activity

Implement the IS DISTINCT FROM operator per SQL99.

Browse Source 
Reused the Expr node to hold DISTINCT which strongly resembles
 the existing OP info. Define DISTINCT_EXPR which strongly resembles
 the existing OPER_EXPR opType, but with handling for NULLs required
 by SQL99.
We have explicit support for single-element DISTINCT comparisons
 all the way through to the executor. But, multi-element DISTINCTs
 are handled by expanding into a comparison tree in gram.y as is done for
 other row comparisons. Per discussions, it might be desirable to move
 this into one or more purpose-built nodes to be handled in the backend.
Define the optional ROW keyword and token per SQL99.
 This allows single-element row constructs, which were formerly disallowed
 due to shift/reduce conflicts with parenthesized a_expr clauses.
Define the SQL99 TREAT() function. Currently, use as a synonym for CAST().
This commit is contained in:
Thomas G. Lockhart
2002-07-04 15:24:11 +00:00
parent c7eea66c39
commit 68d9fbeb55
10 changed files with 438 additions and 100 deletions
Download Patch File Download Diff File Expand all files Collapse all files

17
src/backend/utils/adt/ruleutils.c
View File

@ -3,7 +3,7 @@
* back to source text
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/utils/adt/ruleutils.c,v 1.108 2002/06/13 03:40:49 tgl Exp $
* $Header: /cvsroot/pgsql/src/backend/utils/adt/ruleutils.c,v 1.109 2002/07/04 15:24:07 thomas Exp $
*
* This software is copyrighted by Jan Wieck - Hamburg.
*
@ -1626,6 +1626,21 @@ get_rule_expr(Node *node, deparse_context *context)
get_oper_expr(expr, context);
break;
case DISTINCT_EXPR:
appendStringInfoChar(buf, '(');
Assert(length(args) == 2);
{
/* binary operator */
Node *arg1 = (Node *) lfirst(args);
Node *arg2 = (Node *) lsecond(args);
get_rule_expr(arg1, context);
appendStringInfo(buf, " IS DISTINCT FROM ");
get_rule_expr(arg2, context);
}
appendStringInfoChar(buf, ')');
break;
case FUNC_EXPR:
get_func_expr(expr, context);
break;