mySQL select count，多个表

我有三张桌子：

table1, table2, table3

我试图获取每个表中的总行数以及价格列的总和，例如：

$r['count'] = total rows of all 3 tables combined;
$r['price'] = sum of all prices added together in all 3 tables combined;

这是我的查询：

SELECT COUNT(*) AS `count`, SUM(price) AS `price` FROM `table1` UNION
SELECT COUNT(*) AS `count`, SUM(price) AS `price` FROM `table2` UNION
SELECT COUNT(*) AS `count`, SUM(price) AS `price` FROM `table3`

当我运行此查询时，我得到：

count   price
19      5609399
8       946000
4       0

当在 PHP 中循环时，这又不起作用，因为它们是 3 个单独的值，而我只返回“count = 19 and Price = 5609399”。它们并不是全部都加在一起count or price.

任何帮助是极大的赞赏 ：）

SELECT COUNT(*) AS `count`, SUM(price) AS `price`
FROM
(
SELECT price from `table1` UNION ALL
SELECT price FROM `table2` UNION ALL
SELECT price FROM `table3`
) X

或者通常组合 3 对值

select sum(`count`) `count`, sum(`price`) `price`
FROM
(
SELECT COUNT(*) AS `count`, SUM(price) AS `price` FROM `table1` UNION ALL
SELECT COUNT(*) AS `count`, SUM(price) AS `price` FROM `table2` UNION ALL
SELECT COUNT(*) AS `count`, SUM(price) AS `price` FROM `table3`
) X

一般来说，在合并表时使用 UNION ALL，而不是 UNION，因为 UNION 删除了重复项，所以如果您的计数/总和恰好是

1, 100
1, 100
2, 200

联合查询的结果是

1, 100    # duplicate collapsed
2, 200