ef实现一次查询多个聚合函数的字段

想用ef来写一个统计字段的语句,如下所示

select sum(price) as price_total, sum(amount) as amount_total from table1 

发现似乎实现不了,ef只能 dbContext.Table.Sum(e=>e.price);dbContext.Table.Sum(e=>e.amount)这样一个一个查,没办法一次查询多个聚合函数字段

经过我的研究后,我发现可以曲线救国。

dbContext.Table.GroupBy(e => 1).
                Select(g => new
                {
                    price_total:g.Sum(e => e.Price),
                    amount_total:g.Sum(e => e.Amount)
                }).SingleOrDefault();

生成的sql语句如下,还算可以。

SELECT SUM(`t`.`amount`) AS `remain`, SUM(`t`.`price`) AS `price`
FROM (
    SELECT `e`.*, 1 AS `Key`
    FROM `it_asset` AS `e`
) AS `t`
GROUP BY `t`.`Key`
LIMIT 2

还有一个需要注意的点,如果你需要Sum(amount1-amount2)这样的话,在GroupBy里面千万不能这样写 Sum(e=>e.amount1-e.amount2),得这样写Sum(e=>amount1)-Sum(e=>e.amount2)

原文地址:https://www.cnblogs.com/caijt/p/10956127.html