# 子查询的优势

__*简单子查询*__

+ 子查询通常使 SQL 语句更易于阅读
```10
tidb> SELECT 
   -> table_schema, table_name, table_rows
   -> FROM information_schema.tables
   -> WHERE table_rows ~!@>@!~ (
   ->    SELECT ~!@avg(table_rows)@!~ FROM information_schema.tables);
+--------------+-----------------------------+------------+
| table_schema | table_name                  | table_rows |
+--------------+-----------------------------+------------+
| test         | auto_random_t1_clustered    |    1048576 |
| test         | auto_random_t2_nonclustered |    1048576 |
| world        | city                        |       4079 |
+--------------+-----------------------------+------------+
```
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