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-rw-r--r--src/backend/parser/analyze.c13
-rw-r--r--src/backend/parser/gram.y8
-rw-r--r--src/backend/parser/parse_clause.c19
-rw-r--r--src/test/regress/expected/errors.out23
-rw-r--r--src/test/regress/sql/errors.sql15
5 files changed, 52 insertions, 26 deletions
diff --git a/src/backend/parser/analyze.c b/src/backend/parser/analyze.c
index a9d1fecff5c..60cce378453 100644
--- a/src/backend/parser/analyze.c
+++ b/src/backend/parser/analyze.c
@@ -2018,6 +2018,19 @@ transformReturningList(ParseState *pstate, List *returningList)
/* transform RETURNING identically to a SELECT targetlist */
rlist = transformTargetList(pstate, returningList, EXPR_KIND_RETURNING);
+ /*
+ * Complain if the nonempty tlist expanded to nothing (which is possible
+ * if it contains only a star-expansion of a zero-column table). If we
+ * allow this, the parsed Query will look like it didn't have RETURNING,
+ * with results that would probably surprise the user.
+ */
+ if (rlist == NIL)
+ ereport(ERROR,
+ (errcode(ERRCODE_SYNTAX_ERROR),
+ errmsg("RETURNING must have at least one column"),
+ parser_errposition(pstate,
+ exprLocation(linitial(returningList)))));
+
/* mark column origins */
markTargetListOrigins(pstate, rlist);
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index 8fced4427b1..f9d45777ca7 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -334,7 +334,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
name_list from_clause from_list opt_array_bounds
qualified_name_list any_name any_name_list
any_operator expr_list attrs
- target_list insert_column_list set_target_list
+ target_list opt_target_list insert_column_list set_target_list
set_clause_list set_clause multiple_set_clause
ctext_expr_list ctext_row def_list indirection opt_indirection
reloption_list group_clause TriggerFuncArgs select_limit
@@ -9259,7 +9259,7 @@ select_clause:
* However, this is not checked by the grammar; parse analysis must check it.
*/
simple_select:
- SELECT opt_distinct target_list
+ SELECT opt_distinct opt_target_list
into_clause from_clause where_clause
group_clause having_clause window_clause
{
@@ -12215,6 +12215,10 @@ ctext_row: '(' ctext_expr_list ')' { $$ = $2; }
*
*****************************************************************************/
+opt_target_list: target_list { $$ = $1; }
+ | /* EMPTY */ { $$ = NIL; }
+ ;
+
target_list:
target_el { $$ = list_make1($1); }
| target_list ',' target_el { $$ = lappend($1, $3); }
diff --git a/src/backend/parser/parse_clause.c b/src/backend/parser/parse_clause.c
index 939fa834e0a..87b0c8fd418 100644
--- a/src/backend/parser/parse_clause.c
+++ b/src/backend/parser/parse_clause.c
@@ -2011,6 +2011,20 @@ transformDistinctClause(ParseState *pstate,
true);
}
+ /*
+ * Complain if we found nothing to make DISTINCT. Returning an empty list
+ * would cause the parsed Query to look like it didn't have DISTINCT, with
+ * results that would probably surprise the user. Note: this case is
+ * presently impossible for aggregates because of grammar restrictions,
+ * but we check anyway.
+ */
+ if (result == NIL)
+ ereport(ERROR,
+ (errcode(ERRCODE_SYNTAX_ERROR),
+ is_agg ?
+ errmsg("an aggregate with DISTINCT must have at least one argument") :
+ errmsg("SELECT DISTINCT must have at least one column")));
+
return result;
}
@@ -2115,6 +2129,11 @@ transformDistinctOnClause(ParseState *pstate, List *distinctlist,
true);
}
+ /*
+ * An empty result list is impossible here because of grammar restrictions.
+ */
+ Assert(result != NIL);
+
return result;
}
diff --git a/src/test/regress/expected/errors.out b/src/test/regress/expected/errors.out
index 40615129778..5f8868da26e 100644
--- a/src/test/regress/expected/errors.out
+++ b/src/test/regress/expected/errors.out
@@ -15,26 +15,24 @@ select 1;
--
--
-- SELECT
--- missing relation name
+-- this used to be a syntax error, but now we allow an empty target list
select;
-ERROR: syntax error at or near ";"
-LINE 1: select;
- ^
+--
+(1 row)
+
-- no such relation
select * from nonesuch;
ERROR: relation "nonesuch" does not exist
LINE 1: select * from nonesuch;
^
--- missing target list
-select from pg_database;
-ERROR: syntax error at or near "from"
-LINE 1: select from pg_database;
- ^
-- bad name in target list
select nonesuch from pg_database;
ERROR: column "nonesuch" does not exist
LINE 1: select nonesuch from pg_database;
^
+-- empty distinct list isn't OK
+select distinct from pg_database;
+ERROR: SELECT DISTINCT must have at least one column
-- bad attribute name on lhs of operator
select * from pg_database where nonesuch = pg_database.datname;
ERROR: column "nonesuch" does not exist
@@ -45,12 +43,7 @@ select * from pg_database where pg_database.datname = nonesuch;
ERROR: column "nonesuch" does not exist
LINE 1: ...ect * from pg_database where pg_database.datname = nonesuch;
^
--- bad select distinct on syntax, distinct attribute missing
-select distinct on (foobar) from pg_database;
-ERROR: syntax error at or near "from"
-LINE 1: select distinct on (foobar) from pg_database;
- ^
--- bad select distinct on syntax, distinct attribute not in target list
+-- bad attribute name in select distinct on
select distinct on (foobar) * from pg_database;
ERROR: column "foobar" does not exist
LINE 1: select distinct on (foobar) * from pg_database;
diff --git a/src/test/regress/sql/errors.sql b/src/test/regress/sql/errors.sql
index 2ee707c5c75..cd370b4781e 100644
--- a/src/test/regress/sql/errors.sql
+++ b/src/test/regress/sql/errors.sql
@@ -16,28 +16,25 @@ select 1;
--
-- SELECT
--- missing relation name
+-- this used to be a syntax error, but now we allow an empty target list
select;
-- no such relation
select * from nonesuch;
--- missing target list
-select from pg_database;
-- bad name in target list
select nonesuch from pg_database;
+
+-- empty distinct list isn't OK
+select distinct from pg_database;
+
-- bad attribute name on lhs of operator
select * from pg_database where nonesuch = pg_database.datname;
-- bad attribute name on rhs of operator
select * from pg_database where pg_database.datname = nonesuch;
-
--- bad select distinct on syntax, distinct attribute missing
-select distinct on (foobar) from pg_database;
-
-
--- bad select distinct on syntax, distinct attribute not in target list
+-- bad attribute name in select distinct on
select distinct on (foobar) * from pg_database;
generated by cgit v1.2.3 (git 2.25.1) at 2025-05-31 13:41:57 +0000