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Allow AS to be omitted when specifying an output column name in SELECT

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(or RETURNING), but only when the output name is not any SQL keyword.
This seems as close as we can get to the standard's syntax without a
great deal of thrashing.  Original patch by Hiroshi Saito, amended by me.
This commit is contained in:
Tom Lane
2008-02-15 22:17:06 +00:00
parent cc80f0a340
commit e67867b26c
10 changed files with 119 additions and 51 deletions
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20
src/backend/parser/gram.y
View File

@ -11,7 +11,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/parser/gram.y,v 2.606 2008/02/07 21:07:55 tgl Exp $
* $PostgreSQL: pgsql/src/backend/parser/gram.y,v 2.607 2008/02/15 22:17:06 tgl Exp $
*
* HISTORY
* AUTHOR DATE MAJOR EVENT
@ -477,6 +477,7 @@ static Node *makeXmlExpr(XmlExprOp op, char *name, List *named_args, List *args)
%nonassoc BETWEEN
%nonassoc IN_P
%left POSTFIXOP /* dummy for postfix Op rules */
%nonassoc IDENT /* to support target_el without AS */
%left Op OPERATOR /* multi-character ops and user-defined operators */
%nonassoc NOTNULL
%nonassoc ISNULL
@ -8705,7 +8706,6 @@ target_list:
| target_list ',' target_el { $$ = lappend($1, $3); }
;
/* AS is not optional because shift/red conflict with unary ops */
target_el: a_expr AS ColLabel
{
$$ = makeNode(ResTarget);
@ -8714,6 +8714,22 @@ target_el: a_expr AS ColLabel
$$->val = (Node *)$1;
$$->location = @1;
}
/*
* We support omitting AS only for column labels that aren't
* any known keyword. There is an ambiguity against postfix
* operators: is "a ! b" an infix expression, or a postfix
* expression and a column label? We prefer to resolve this
* as an infix expression, which we accomplish by assigning
* IDENT a precedence higher than POSTFIXOP.
*/
| a_expr IDENT
{
$$ = makeNode(ResTarget);
$$->name = $2;
$$->indirection = NIL;
$$->val = (Node *)$1;
$$->location = @1;
}
| a_expr
{
$$ = makeNode(ResTarget);

10
src/interfaces/ecpg/preproc/preproc.y
View File

@ -1,4 +1,4 @@
/* $PostgreSQL: pgsql/src/interfaces/ecpg/preproc/preproc.y,v 1.360 2008/02/14 14:54:48 meskes Exp $ */
/* $PostgreSQL: pgsql/src/interfaces/ecpg/preproc/preproc.y,v 1.361 2008/02/15 22:17:06 tgl Exp $ */
/* Copyright comment */
%{
@ -521,8 +521,9 @@ add_typedef(char *name, char * dimension, char * length, enum ECPGttype type_enu
%nonassoc OVERLAPS
%nonassoc BETWEEN
%nonassoc IN_P
%left POSTFIXOP /* dummy for postfix Op rules */
%left Op OPERATOR /* multi-character ops and user-defined operators */
%left POSTFIXOP /* dummy for postfix Op rules */
%nonassoc IDENT /* to support target_el without AS */
%left Op OPERATOR /* multi-character ops and user-defined operators */
%nonassoc NOTNULL
%nonassoc ISNULL
%nonassoc IS NULL_P TRUE_P FALSE_P UNKNOWN
@ -4695,9 +4696,10 @@ target_list: target_list ',' target_el
{ $$ = $1; }
;
/* AS is not optional because shift/red conflict with unary ops */
target_el: a_expr AS ColLabel
{ $$ = cat_str(3, $1, make_str("as"), $3); }
| a_expr IDENT
{ $$ = cat_str(3, $1, make_str("as"), $2); }
| a_expr
{ $$ = $1; }
| '*'

4
src/test/regress/expected/plpgsql.out
View File

@ -2337,9 +2337,9 @@ begin
end loop;
return 5;
end;$$ language plpgsql;
ERROR: syntax error at or near "fought"
ERROR: syntax error at or near "the"
LINE 1: select I fought the law, the law won
^
^
QUERY: select I fought the law, the law won
CONTEXT: SQL statement in PL/PgSQL function "bad_sql2" near line 3
-- a RETURN expression is mandatory, except for void-returning