diff --git a/docs/mysql.md b/docs/mysql.md
index 3c2d01b..d338130 100644
--- a/docs/mysql.md
+++ b/docs/mysql.md
@@ -173,6 +173,12 @@ ALTER TABLE t1 RENAME TO t2;
 ALTER TABLE t1 RENAME c1 TO c2 ;
 ```
 
+将列c1的数据类型改为datatype
+
+```sql
+ALTER TABLE t1 MODIFY c1 datatype;
+```
+
 删除表中的所有数据
 
 ```sql