Postgres: Complete DELETE FROM grammar (#2791)

* Postgres: Complete DELETE FROM grammar

* Add DELETE statement to WITH grammar

* Add WITH RECURSIVE example

Co-authored-by: Barry Pollard <barry@tunetheweb.com>

src/sqlfluff/dialects/dialect_ansi.py

@@ -2159,6 +2159,7 @@ class SelectStatementSegment(BaseSegment):
     NonWithNonSelectableGrammar=OneOf(
         Ref("UpdateStatementSegment"),
         Ref("InsertStatementSegment"),
+        Ref("DeleteStatementSegment"),
     ),
     # Things that behave like select statements, which can form part of set expressions.
     NonSetSelectableGrammar=OneOf(

src/sqlfluff/dialects/dialect_postgres.py

@@ -3671,40 +3671,6 @@ class ValuesClauseSegment(BaseSegment):
     )
 
 
-@postgres_dialect.segment()
-class DeleteUsingClauseSegment(BaseSegment):
-    """USING clause."""
-
-    type = "using_clause"
-    match_grammar = StartsWith(
-        "USING",
-        terminator="WHERE",
-        enforce_whitespace_preceding_terminator=True,
-    )
-
-    parse_grammar = Sequence(
-        "USING",
-        Indent,
-        Delimited(
-            Ref("TableExpressionSegment"),
-        ),
-        Dedent,
-    )
-
-
-@postgres_dialect.segment()
-class FromClauseTerminatingUsingWhereSegment(
-    ansi_dialect.get_segment("FromClauseSegment")  # type: ignore
-):
-    """Copy `FROM` terminator statement to support `USING` in specific circumstances."""
-
-    match_grammar = StartsWith(
-        "FROM",
-        terminator=OneOf(Ref.keyword("USING"), Ref.keyword("WHERE")),
-        enforce_whitespace_preceding_terminator=True,
-    )
-
-
 @postgres_dialect.segment(replace=True)
 class DeleteStatementSegment(BaseSegment):
     """A `DELETE` statement.
@@ -3713,14 +3679,26 @@ class DeleteStatementSegment(BaseSegment):
     """
 
     type = "delete_statement"
-    # TODO Implement WITH RECURSIVE
     match_grammar = StartsWith("DELETE")
     parse_grammar = Sequence(
         "DELETE",
+        "FROM",
         Ref.keyword("ONLY", optional=True),
-        Ref("FromClauseTerminatingUsingWhereSegment"),
-        # TODO Implement Star and As Alias
-        Ref("DeleteUsingClauseSegment", optional=True),
+        Ref("TableReferenceSegment"),
+        Ref("StarSegment", optional=True),
+        Ref("AsAliasExpressionSegment", optional=True),
+        Sequence(
+            "USING",
+            Indent,
+            Delimited(
+                Sequence(
+                    Ref("TableExpressionSegment"),
+                    Ref("AsAliasExpressionSegment", optional=True),
+                ),
+            ),
+            Dedent,
+            optional=True,
+        ),
         OneOf(
             Sequence("WHERE", "CURRENT", "OF", Ref("ObjectReferenceSegment")),
             Ref("WhereClauseSegment"),
@@ -3730,11 +3708,12 @@ class DeleteStatementSegment(BaseSegment):
             "RETURNING",
             OneOf(
                 Ref("StarSegment"),
-                Sequence(
-                    Ref("ExpressionSegment"),
-                    Ref("AliasSegment", optional=True),
+                Delimited(
+                    Sequence(
+                        Ref("ExpressionSegment"),
+                        Ref("AsAliasExpressionSegment", optional=True),
+                    ),
                 ),
-                optional=True,
             ),
             optional=True,
         ),

test/fixtures/dialects/postgres/postgres_delete.sql

@@ -1,12 +1,41 @@
-DELETE FROM films WHERE kind <> 'Musical';
-
 DELETE FROM films;
 
-DELETE FROM tasks WHERE status = 'DONE' RETURNING *;
+DELETE FROM ONLY films;
+
+DELETE FROM films *;
+
+DELETE FROM films AS f;
+
+DELETE FROM films USING producers
+  WHERE producer_id = producers.id AND producers.name = 'foo';
+
+DELETE FROM films AS f USING producers AS p
+  WHERE f.producer_id = p.id AND p.name = 'foo';
+
+DELETE FROM films AS f USING producers AS p, actors AS a
+  WHERE f.producer_id = p.id AND p.name = 'foo'
+    AND f.actor_id = a.id AND a.name = 'joe cool';
 
 DELETE FROM tasks WHERE CURRENT OF c_tasks;
 
-DELETE FROM some_table
-USING other_table
-WHERE other_table.col = some_table.col
+DELETE FROM films WHERE kind <> 'Musical';
+
+DELETE FROM tasks WHERE status = 'DONE' RETURNING *;
+
+DELETE FROM tasks WHERE status = 'DONE' RETURNING actor_id;
+
+DELETE FROM tasks WHERE status = 'DONE' RETURNING actor_id as a_id;
+
+DELETE FROM tasks WHERE status = 'DONE' RETURNING actor_id, producer_id;
 
+DELETE FROM tasks WHERE status = 'DONE' RETURNING actor_id as a_id, producer_id as p_id;
+
+WITH test as (select foo from bar)
+DELETE FROM films;
+
+WITH RECURSIVE t(n) AS (
+    VALUES (1)
+  UNION ALL
+    SELECT n+1 FROM t WHERE n < 100
+)
+DELETE FROM films;