在 MySQL 中仅从特定单元格获取总和?
mysqlmysqli database
对于仅特定单元格，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 -> ); Query OK, 0 rows affected (0.87 sec)
使用 insert 命令在表中插入一些记录 −
mysql> insert into DemoTable1370 values('Adam Smith',56);
Query OK, 1 row affected (0.20 sec)
mysql> insert into DemoTable1370 values('Chris Brown',67);
Query OK, 1 row affected (0.17 sec)
mysql> insert into DemoTable1370 values('Adam Smith',69);
Query OK, 1 row affected (0.20 sec)
mysql> insert into DemoTable1370 values('David Miller',98);
Query OK, 1 row affected (0.12 sec)
mysql> insert into DemoTable1370 values('John Smith',59);
Query OK, 1 row affected (0.13 sec)
mysql> insert into DemoTable1370 values('Adam Smith',79);
Query OK, 1 row affected (0.11 sec)
mysql> insert into DemoTable1370 values('Chris Brown',77);
Query OK, 1 row affected (0.17 sec)
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)
