[sqllab] Fix limit parsing bug when using limit-offset comma notation (…

…#7912)

* Fix limit parsing bug when using limit-offset comma notation

* Use native sqlparse semantics to find limit

* black

superset/sql_parse.py

@@ -182,7 +182,10 @@ def _extract_limit_from_query(self, statement):
             _, token = statement.token_next(idx=idx)
             if token:
                 if isinstance(token, IdentifierList):
-                    _, token = token.token_next(idx=-1)
+                    # In case of "LIMIT <offset>, <limit>", find comma and extract
+                    # first succeeding non-whitespace token
+                    idx, _ = token.token_next_by(m=(sqlparse.tokens.Punctuation, ","))
+                    _, token = token.token_next(idx=idx)
                 if token and token.ttype == sqlparse.tokens.Literal.Number.Integer:
                     return int(token.value)
 

tests/db_engine_specs_test.py

@@ -175,12 +175,12 @@ def test_extract_limit_from_query(self, engine_spec_class=MySQLEngineSpec):
         q2 = "select * from (select * from my_subquery limit 10) where col=1 limit 20"
         q3 = "select * from (select * from my_subquery limit 10);"
         q4 = "select * from (select * from my_subquery limit 10) where col=1 limit 20;"
-        q5 = "select * from mytable limit 10, 20"
+        q5 = "select * from mytable limit 20, 10"
         q6 = "select * from mytable limit 10 offset 20"
         q7 = "select * from mytable limit"
         q8 = "select * from mytable limit 10.0"
         q9 = "select * from mytable limit x"
-        q10 = "select * from mytable limit x, 20"
+        q10 = "select * from mytable limit 20, x"
         q11 = "select * from mytable limit x offset 20"
 
         self.assertEqual(engine_spec_class.get_limit_from_sql(q0), None)