仅从MySQL中的特定单元获取总和？
对于仅特定的单元格，使用WHERE设置条件并使用聚合函数SUM()进行添加。让我们首先创建一个表-
mysql> create table DemoTable1370 -> ( -> StudentName varchar(20), -> Marks int -> );
使用插入命令在表中插入一些记录-
mysql> insert into DemoTable1370 values('Adam Smith',56);
mysql> insert into DemoTable1370 values('Chris Brown',67);
mysql> insert into DemoTable1370 values('Adam Smith',69);
mysql> insert into DemoTable1370 values('David Miller',98);
mysql> insert into DemoTable1370 values('John Smith',59);
mysql> insert into DemoTable1370 values('Adam Smith',79);
mysql> insert into DemoTable1370 values('Chris Brown',77);使用select语句显示表中的所有记录-
mysql> select * from DemoTable1370;
这将产生以下输出-
+--------------+-------+ | StudentName | Marks | +--------------+-------+ | Adam Smith | 56 | | Chris Brown | 67 | | Adam Smith | 69 | | David Miller | 98 | | John Smith | 59 | | Adam Smith | 79 | | Chris Brown | 77 | +--------------+-------+ 7 rows in set (0.00 sec)
这是从特定单元格获取总和的查询-
mysql> select sum(Marks) AS Total from DemoTable1370 where StudentName='Adam Smith';
这将产生以下输出-
+-------+ | Total | +-------+ | 204 | +-------+ 1 row in set (0.00 sec)