计算大于和小于特定数字的值并在单独的 MySQL 列中显示计数?
mysqlmysqli database更新于 2024/4/4 7:34:00
为此，您可以将 COUNT() 与 CASE STATEMENT 一起使用。让我们首先创建一个表 −
mysql> create table DemoTable ( Score int ); Query OK, 0 rows affected (0.71 sec)
使用 insert 命令在表中插入一些记录 −
mysql> insert into DemoTable values(40); Query OK, 1 row affected (0.77 sec) mysql> insert into DemoTable values(48); Query OK, 1 row affected (0.12 sec) mysql> insert into DemoTable values(59); Query OK, 1 row affected (0.10 sec) mysql> insert into DemoTable values(33); Query OK, 1 row affected (0.20 sec) mysql> insert into DemoTable values(38); Query OK, 1 row affected (0.09 sec) mysql> insert into DemoTable values(89); Query OK, 1 row affected (0.11 sec) mysql> insert into DemoTable values(35); Query OK, 1 row affected (0.12 sec)
使用 select 语句显示表中的所有记录 −
mysql> select *from DemoTable;
这将产生以下输出 −
+-------+ | Score | +-------+ | 40 | | 48 | | 59 | | 33 | | 38 | | 89 | | 35 | +-------+ 7 rows in set (0.00 sec)
以下查询用于计算大于和小于特定数字的值并在单独的列中显示计数 −
mysql> select count( case when Score > 45 then 1 end) as CountOfValueGreaterThan45, count( case when Score <= 45 then 1 end) as CountOfValueLessThanOrEqualTo45 from DemoTable;
这将产生以下输出 −
+---------------------------+---------------------------------+ | CountOfValueGreaterThan45 | CountOfValueLessThanOrEqualTo45 | +---------------------------+---------------------------------+ | 3 | 4 | +---------------------------+---------------------------------+ 1 row in set (0.00 sec)
