在MySQL中显示来自对应重复ID的最高数量
要显示来自对应重复ID的最高金额，请MAX()与GROUPBY子句一起使用-
mysql> create table DemoTable2003 ( CustomerId int, Amount int );
使用插入命令在表中插入一些记录-
mysql> insert into DemoTable2003 values(101,560); mysql> insert into DemoTable2003 values(102,1080); mysql> insert into DemoTable2003 values(101,570); mysql> insert into DemoTable2003 values(102,870); mysql> insert into DemoTable2003 values(101,460);
使用select语句显示表中的所有记录-
mysql> select * from DemoTable2003;
这将产生以下输出-
+------------+--------+ | CustomerId | Amount | +------------+--------+ | 101 | 560 | | 102 | 1080 | | 101 | 570 | | 102 | 870 | | 101 | 460 | +------------+--------+ 5 rows in set (0.00 sec)
这是显示对应重复ID中最高金额的查询-
mysql> select CustomerId, max(Amount) from DemoTable2003 group by CustomerId;
这将产生以下输出-
+------------+-------------+ | CustomerId | max(Amount) | +------------+-------------+ | 101 | 570 | | 102 | 1080 | +------------+-------------+ 2 rows in set (0.00 sec)