diff --git a/v2/sketch.py b/v2/sketch.py
index 350827c..1733942 100644
--- a/v2/sketch.py
+++ b/v2/sketch.py
@@ -109,9 +109,9 @@ class Sketch:
                 if isinstance(v, bool):
                     default_field[k] = 'Nullable(UInt8)'
 
-                sql = f'alter table {db}.{tb} add column `{k}` {default_field[k]}'
-                print(sql)
                 try:
+                    sql = f'alter table {db}.{tb} add column `{k}` {default_field[k]}'
+                    print(sql)
                     self.db_client.execute(sql)
                 except Exception as e:
                     print(f'添加字段 {k} 失败,同步数据库表结构')