首先按升序查询一行中的非空值，然后显示 NULL 值
mysqlmysqli database
为此，请使用 ORDER BY ISNULL()。让我们首先创建一个表 −
mysql> create table DemoTable669 ( StudentId int NOT NULL AUTO_INCREMENT PRIMARY KEY, StudentScore int ); Query OK, 0 rows affected (0.55 sec)
使用 insert 命令在表中插入一些记录 −
mysql> insert into DemoTable669(StudentScore) values(45) ; Query OK, 1 row affected (0.80 sec) mysql> insert into DemoTable669(StudentScore) values(null); Query OK, 1 row affected (0.17 sec) mysql> insert into DemoTable669(StudentScore) values(89); Query OK, 1 row affected (0.10 sec) mysql> insert into DemoTable669(StudentScore) values(null); Query OK, 1 row affected (0.15 sec)
使用 select 语句显示表中的所有记录 −
mysql> select *from DemoTable669;
这将产生以下输出 −
+-----------+--------------+ | StudentId | StudentScore | +-----------+--------------+ | 1 | 45 | | 2 | NULL | | 3 | 89 | | 4 | NULL | +-----------+--------------+ 4 rows in set (0.00 sec)
以下查询按升序显示非空值。随后将显示空值 −
mysql> select *from DemoTable669 ORDER BY ISNULL(StudentScore),StudentScore;
这将产生以下输出 −
+-----------+--------------+ | StudentId | StudentScore | +-----------+--------------+ | 1 | 45 | | 3 | 89 | | 2 | NULL | | 4 | NULL | +-----------+--------------+ 4 rows in set (0.00 sec)
