当我运行一条联合查询的sql语句时报如下错误：
[Err] 1248 - Every derived table must have its own alias，大概意思是每一张派生表必须要有自己的别名。这里加上别名即可。
原先sql：
select * from t_test t1 where t1.content like '%test%'
Union all
select * from
(select * from t_test t2 where t2.content not like '%test%' order by t2.content asc);
加上别名之后：
select * from t_test t1 where t1.content like '%test%'
Union all
select * from
(select * from t_test t2 where t2.content not like '%test%' order by t2.content asc) d;
再运行一遍之后问题解决
