基于索引上锁，而不是针对选出来的具体的行
root@sakila 10:14:32>show index from tab_no_index \G
*************************** 1. row ***************************
        Table: tab_no_index
   Non_unique: 1
     Key_name: id
 Seq_in_index: 1
  Column_name: id
    Collation: A
  Cardinality: 5
     Sub_part: NULL
       Packed: NULL
         Null: YES
   Index_type: BTREE
      Comment:
Index_comment:
1 row in set (0.00 sec)

第一个会话
root@sakila 10:18:39>select * from tab_no_index where id=1 and name='1' for update;
+------+------+
| id   | name |
+------+------+
|    1 | 1    |
+------+------+
1 row in set (0.00 sec)

第二个会话
root@sakila 10:18:42>select * from tab_no_index where id=1 and name='4' for update;
ERROR 1205 (HY000): Lock wait timeout exceeded; try restarting transaction