Parse INSERT with subquery when lacking column names (#1586)

Author: iffyio

src/parser/mod.rs

@@ -11329,14 +11329,19 @@ impl<'a> Parser<'a> {
                 if self.parse_keywords(&[Keyword::DEFAULT, Keyword::VALUES]) {
                     (vec![], None, vec![], None)
                 } else {
-                    let columns = self.parse_parenthesized_column_list(Optional, is_mysql)?;
+                    let (columns, partitioned, after_columns) = if !self.peek_subquery_start() {
+                        let columns = self.parse_parenthesized_column_list(Optional, is_mysql)?;
 
-                    let partitioned = self.parse_insert_partition()?;
-                    // Hive allows you to specify columns after partitions as well if you want.
-                    let after_columns = if dialect_of!(self is HiveDialect) {
-                        self.parse_parenthesized_column_list(Optional, false)?
+                        let partitioned = self.parse_insert_partition()?;
+                        // Hive allows you to specify columns after partitions as well if you want.
+                        let after_columns = if dialect_of!(self is HiveDialect) {
+                            self.parse_parenthesized_column_list(Optional, false)?
+                        } else {
+                            vec![]
+                        };
+                        (columns, partitioned, after_columns)
                     } else {
-                        vec![]
+                        Default::default()
                     };
 
                     let source = Some(self.parse_query()?);
@@ -11431,6 +11436,14 @@ impl<'a> Parser<'a> {
         }
     }
 
+    /// Returns true if the immediate tokens look like the
+    /// beginning of a subquery. `(SELECT ...`
+    fn peek_subquery_start(&mut self) -> bool {
+        let [maybe_lparen, maybe_select] = self.peek_tokens();
+        Token::LParen == maybe_lparen
+            && matches!(maybe_select, Token::Word(w) if w.keyword == Keyword::SELECT)
+    }
+
     fn parse_conflict_clause(&mut self) -> Option<SqliteOnConflict> {
         if self.parse_keywords(&[Keyword::OR, Keyword::REPLACE]) {
             Some(SqliteOnConflict::Replace)

tests/sqlparser_common.rs

@@ -10964,6 +10964,8 @@ fn insert_into_with_parentheses() {
         Box::new(GenericDialect {}),
     ]);
     dialects.verified_stmt("INSERT INTO t1 (id, name) (SELECT t2.id, t2.name FROM t2)");
+    dialects.verified_stmt("INSERT INTO t1 (SELECT t2.id, t2.name FROM t2)");
+    dialects.verified_stmt(r#"INSERT INTO t1 ("select", name) (SELECT t2.name FROM t2)"#);
 }
 
 #[test]