Question

假设我想在3个不同的表上执行3个不同的总和

2017-01-29 03:28:09 GMT

我想在一个声明中执行这些查询。

SELECT sum(`diepoints`)  as exp FROM `dies` where user='coder'
SELECT sum(`winpoints`)  as rev FROM `wins` where user='coder'
SELECT sum(`debtpoints`) as deb FROM `debts` where user='coder'

然后把它们放在下面。

$resource1= $con->query(SELECT sum(`diepoints`)  as exp FROM `dies` where user='coder');
$resource2 = $con->query(SELECT sum(`winpoints`)  as rev FROM `wins` where user='coder');
$resource3 = $con->query(SELECT sum(`debtpoints`) as deb FROM `debts` where user='coder');

关于如何组合这些查询的任何帮助说明都会很棒。

Answer 1

一种简单的方法是子查询：

SELECT (SELECT sum(`diepoints`)  as exp FROM `dies` where user='coder') as exp,
       (SELECT sum(`winpoints`)  as rev FROM `wins` where user='coder') as rev,
       (SELECT sum(`debtpoints`) as deb FROM `debts` where user='coder') as deb

Answer 2

使用如下子查询在一行中选择它们：

select
(SELECT sum(`diepoints`)  as exp FROM `dies` where user='coder') exp,
(SELECT sum(`winpoints`)  as rev FROM `wins` where user='coder') rev,
(SELECT sum(`debtpoints`) as deb FROM `debts` where user='coder') deb

Mysql在单个php页面上进行多个查询以对各个表进行求和

2 个答案: