锁定查询结果 SELECT FOR UPDATE 
=============================================



OceanBase 支持 MVCC 特性，读是快照读，不阻塞写，是 SELECT 语句还有个特殊的用法可以阻塞写。示例如下：

```javascript
obclient> select w_name, w_ytd, w_tax from ware where w_id=1 for update;
+------------+---------+--------+
| w_name     | w_ytd   | w_tax  |
+------------+---------+--------+
| n1P4zYo8OH | 1200.00 | 0.1868 |
+------------+---------+--------+
1 row in set (0.01 sec)
```