如果初始行是随机的，其余行按条件排序，那么如何使用 MySQL 选择行?
mysqlmysqli database
为此，您可以使用 ORDER BY CASE 语句。让我们创建一个表 −
mysql> create table DemoTable1926 ( Position varchar(20), Number int ); Query OK, 0 rows affected (0.00 sec)
使用 insert 命令在表中插入一些记录 −
mysql> insert into DemoTable1926 values('Highest',50);
Query OK, 1 row affected (0.00 sec)
mysql> insert into DemoTable1926 values('Highest',30);
Query OK, 1 row affected (0.00 sec)
mysql> insert into DemoTable1926 values('Lowest',100);
Query OK, 1 row affected (0.00 sec)
mysql> insert into DemoTable1926 values('Lowest',120);
Query OK, 1 row affected (0.00 sec)
mysql> insert into DemoTable1926 values('Lowest',90);
Query OK, 1 row affected (0.00 sec)
使用 select 语句显示表中的所有记录 −
mysql> select * from DemoTable1926;
这将产生以下输出 −
+----------+--------+ | Position | Number | +----------+--------+ | Highest | 50 | | Highest | 30 | | Lowest | 100 | | Lowest | 120 | | Lowest | 90 | +----------+--------+ 5 rows in set (0.00 sec)
如果初始行是随机的，其余行按条件排序，则以下查询用于选择行 −
mysql> select * from DemoTable1926 order by Position desc,case Position when 'Highest' then rand() else Number end asc;
这将产生以下输出 −
+----------+--------+ | Position | Number | +----------+--------+ | Lowest | 90 | | Lowest | 100 | | Lowest | 120 | | Highest | 50 | | Highest | 30 | +----------+--------+ 5 rows in set (0.00 sec)
