MySQL中ORDER BY子句有什么用？

MySQL ORDER BY 子句用于指定查询结果的排序。关键字 ORDER BY 后面必须跟有我们要排序的列的名称。例如，我们要根据“价格”列对名为“ratelist”的下表进行排序 -

mysql> Select * from ratelist;
+----+------+-------+
| Sr | Item | Price |
+----+------+-------+
| 1  | A    |  502  |
| 2  | B    |  630  |
| 3  | C    | 1005  |
| 4  | h    |  850  |
| 5  | T    |  250  | 
+----+------+-------+
5 rows in set (0.05 sec)

可以借助 ORDER BY 子句来完成排序，如下所示 -

mysql> Select * from ratelist ORDER BY Price;
+----+------+-------+
| Sr | Item | Price |
+----+------+-------+
| 5  | T    |  250  |
| 1  | A    |  502  |
| 2  | B    |  630  |
| 4  | h    |  850  |
| 3  | C    | 1005  | 
+----+------+-------+
5 rows in set (0.01 sec)

上面的查询根据默认排序顺序（即升序）的价格对表格进行排序。