feat(mysql): support ZEROFILL column attribute

- Implemented `_parse_types` in `MySQL.Parser` to consume the `ZEROFILL` token and store it in the DataType expression.
- Updated `datatype_sql` in `MySQL.Generator` to output `ZEROFILL` when the attribute is present.

This fixes parsing errors encountered when processing legacy MySQL schemas containing numeric columns with the zerofill property.

Author: nian0114

sqlglot/dialects/mysql.py

@@ -702,6 +702,14 @@ def _parse_set_item_names(self) -> exp.Expression:
 
             return self.expression(exp.SetItem, this=charset, collate=collate, kind="NAMES")
 
+        def _parse_types(self, *args, **kwargs) -> t.Optional[exp.Expression]:
+            dtype = super()._parse_types(*args, **kwargs)
+            
+            if dtype and self._match_text_seq("ZEROFILL"):
+                dtype.set("zerofill", True)
+            
+            return dtype
+
         def _parse_type(
             self, parse_interval: bool = True, fallback_to_identifier: bool = False
         ) -> t.Optional[exp.Expression]:
@@ -1211,6 +1219,8 @@ def datatype_sql(self, expression: exp.DataType) -> str:
             if expression.this in self.UNSIGNED_TYPE_MAPPING:
                 result = f"{result} UNSIGNED"
 
+            if expression.args.get("zerofill"):
+                result = f"{result} ZEROFILL"
             return result
 
         def jsonarraycontains_sql(self, expression: exp.JSONArrayContains) -> str:

tests/dialects/test_mysql.py

@@ -26,6 +26,7 @@ def test_ddl(self):
         self.validate_identity("CREATE TABLE foo (a BIGINT, INDEX USING BTREE (b))")
         self.validate_identity("CREATE TABLE foo (a BIGINT, FULLTEXT INDEX (b))")
         self.validate_identity("CREATE TABLE foo (a BIGINT, SPATIAL INDEX (b))")
+        self.validate_identity("CREATE TABLE foo (a INT UNSIGNED ZEROFILL)")
         self.validate_identity("ALTER TABLE t1 ADD COLUMN x INT, ALGORITHM=INPLACE, LOCK=EXCLUSIVE")
         self.validate_identity("ALTER TABLE t ADD INDEX `i` (`c`)")
         self.validate_identity("ALTER TABLE t ADD UNIQUE `i` (`c`)")