如何对MySQL中的列元素求和？
使用聚合函数sum()对MySQL中列的元素求和。语法如下-
select sum(yourColumnName1) as anyVariableName1,sum(yourColumnName2) as anyVariableName2,sum(yourColumnName3) as anyVariableName3,............N from yourTableName;
为了理解上述语法，让我们创建一个表。以下是创建表的查询-
mysql> create table SumDemoOnColumns −> ( −> First int, −> Second int, −> Third int −> );
使用insert命令在表中插入一些数据。查询如下-
mysql> insert into SumDemoOnColumns values(10,20,30); mysql> insert into SumDemoOnColumns values(40,50,60); mysql> insert into SumDemoOnColumns values(70,80,90); mysql> insert into SumDemoOnColumns values(100,110,120);
使用select语句显示表中的所有记录。查询如下-
mysql> select *from SumDemoOnColumns;
以下是输出-
+-------+--------+-------+ | First | Second | Third | +-------+--------+-------+ | 10 | 20 | 30 | | 40 | 50 | 60 | | 70 | 80 | 90 | | 100 | 110 | 120 | +-------+--------+-------+ 4 rows in set (0.00 sec)
以下是获取列总和的查询-
mysql> select sum(First) as First,sum(Second) as Second,sum(Third) as Third from SumDemoOnColumns;
以下是输出-
+-------+--------+-------+ | First | Second | Third | +-------+--------+-------+ | 220 | 260 | 300 | +-------+--------+-------+ 1 row in set (0.00 sec)
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