feat(mysql): support ZEROFILL column attribute (#6400)

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

Author: nian0114

sqlglot/dialects/mysql.py

@@ -464,6 +464,7 @@ class Parser(parser.Parser):
             "INDEX": lambda self: self._parse_index_constraint(),
             "KEY": lambda self: self._parse_index_constraint(),
             "SPATIAL": lambda self: self._parse_index_constraint(kind="SPATIAL"),
+            "ZEROFILL": lambda self: self.expression(exp.ZeroFillColumnConstraint),
         }
 
         ALTER_PARSERS = {

sqlglot/expressions.py

@@ -1972,6 +1972,10 @@ class AutoIncrementColumnConstraint(ColumnConstraintKind):
     pass
 
 
+class ZeroFillColumnConstraint(ColumnConstraint):
+    arg_types = {}
+
+
 class PeriodForSystemTimeConstraint(ColumnConstraintKind):
     arg_types = {"this": True, "expression": True}
 

sqlglot/generator.py

@@ -5434,3 +5434,6 @@ def initcap_sql(self, expression: exp.Initcap) -> str:
                 delimiters = None
 
         return self.func("INITCAP", expression.this, delimiters)
+
+    def zerofillcolumnconstraint_sql(self, expression: exp.ZeroFillColumnConstraint) -> str:
+        return "ZEROFILL"

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`)")