MySQL 如何添加列值而不使用聚合函数

您可以添加列值而不使用聚合函数如sum()。语法如下 −

SELECT *,(yourColumnName1+yourColumnName2+yourColumnName3,… N) as
anyVariableName from yourTableName;

为了理解上述语法，让我们创建一个表。创建表的查询语句如下 −

mysql> create table AddingColumnDemo
    -> (
    -> StudentId int,
    -> StudentName varchar(20),
    -> MathMarks int,
    -> PhysicsMarks int,
    -> ChemistryMarks int
    -> );
Query OK, 0 rows affected (0.82 sec)

使用insert命令在表中插入记录。查询语句如下 −

mysql> insert into AddingColumnDemo values(1,'John',35,45,76);
Query OK, 1 row affected (0.25 sec)

mysql> insert into AddingColumnDemo values(2,'Bob',67,76,88);
Query OK, 1 row affected (0.19 sec)

mysql> insert into AddingColumnDemo values(3,'Carol',45,56,43);
Query OK, 1 row affected (0.16 sec)

mysql> insert into AddingColumnDemo values(4,'Mike',82,75,71);
Query OK, 1 row affected (0.21 sec)

mysql> insert into AddingColumnDemo values(5,'Sam',92,89,88);
Query OK, 1 row affected (0.23 sec)

使用select语句显示表中的所有记录−

mysql> select *from AddingColumnDemo;

以下是显示表的记录的输出−

+-----------+-------------+-----------+--------------+----------------+
| StudentId | StudentName | MathMarks | PhysicsMarks | ChemistryMarks |
+-----------+-------------+-----------+--------------+----------------+
|          1| John        | 35        | 45           |76              |
|          2| Bob         | 67        | 76           |88              |
|          3| Carol       | 45        | 56           |43              |
|          4| Mike        | 82        | 75           |71              |
|          5| Sam         | 92        | 89           |88              |
+-----------+-------------+------------+-------------+----------------+
5 rows in set (0.00 sec)

现在让我们实现在MySQL中添加列值的查询 −

mysql> select *,(MathMarks+PhysicsMarks+ChemistryMarks) as TotalResult from AddingColumnDemo;

以下是显示TotalResult列中列值总和的输出−

+-----------+-------------+-----------+--------------+----------------+-------------+
| StudentId | StudentName | MathMarks | PhysicsMarks | ChemistryMarks | TotalResult |
+-----------+-------------+-----------+--------------+----------------+-------------+
|          1| John        | 35        | 45           | 76             |156          |
|          2| Bob         | 67        | 76           | 88             |231          |
|          3| Carol       | 45        | 56           | 43             |144          |
|          4| Mike        | 82        | 75           | 71             |228          |
|          5| Sam         | 92        | 89           | 88             |269          |
+-----------+-------------+-----------+--------------+----------------+-------------+
5 rows in set (0.00 sec)

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