MySQL查询来计算不同值的出现并将结果显示在新列中？
让我们首先创建一个表-
mysql> create table DemoTable ( Value int );
使用插入命令在表中插入一些记录-
mysql> insert into DemoTable values(80); mysql> insert into DemoTable values(90); mysql> insert into DemoTable values(90); mysql> insert into DemoTable values(80); mysql> insert into DemoTable values(100); mysql> insert into DemoTable values(90);
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-
+-------+ | Value | +-------+ | 80 | | 90 | | 90 | | 80 | | 100| | 90 | +-------+ 6 rows in set (0.00 sec)
以下是对不同值的出现进行计数的查询-
mysql> select Value,count(*) from DemoTable group by Value;
这将产生以下输出-
+-------+----------+ | Value | count(*) | +-------+----------+ | 80 | 2 | | 90 | 3 | | 100 | 1 | +-------+----------+ 3 rows in set (0.00 sec)