在MySQL中基于表值添加整数的有效方法？
您需要使用GROUPBY子句。让我们首先创建一个-
mysql> create table DemoTable1443 -> ( -> StudentId int, -> StudentScore int -> );
使用insert在表中插入一些记录-
mysql> insert into DemoTable1443 values(100,78); mysql> insert into DemoTable1443 values(101,89); mysql> insert into DemoTable1443 values(100,88); mysql> insert into DemoTable1443 values(101,97);
使用选择显示表中的所有记录-
mysql> select * from DemoTable1443;
这将产生以下输出-
+-----------+--------------+ | StudentId | StudentScore | +-----------+--------------+ | 100 | 78 | | 101 | 89 | | 100 | 88 | | 101 | 97 | +-----------+--------------+ 4 rows in set (0.00 sec)
以下是基于表值添加整数的查询-
mysql> select StudentId,sum(StudentScore) from DemoTable1443 -> group by StudentId;
这将产生以下输出-
+-----------+-------------------+ | StudentId | sum(StudentScore) | +-----------+-------------------+ | 100 | 166 | | 101 | 186 | +-----------+-------------------+ 2 rows in set (0.00 sec)