Question

我正在处理一个非常棘手的SQL查询，我想将其转换为LINQ。

你认为有可能吗？

WITH ConditionalChecks AS (
    SELECT c.ItemId FROM ConditionalProperties c, Properties p
    WHERE c.PropertyId = p.Id AND c.IsChecked = 1 AND (

        (p.SystemName = 'eatable') OR
        (p.SystemName = 'diy')

    )
),

ConditionalCount AS (
    SELECT ItemId, Count(*) AS NumTrue FROM ConditionalChecks
    GROUP BY ItemId
),

ItemResult AS (
    SELECT * FROM ConditionalCount c, Items i
    WHERE c.ItemId = i.Id
)

SELECT * FROM ItemResult
WHERE NumTrue = 2

任何提示都表示赞赏！

Answer 1

LINQ可以轻松聚合这样的查询。

var conditionalChecksQuery = 
    from c in db.ConditionalProperties
    where c.IsChecked == 1  // or 'true', if boolean
    join p in db.Properties on c.PropertyId equals p.Id
    where p.SystemName == "eatable" || p.SystemName == "diy"
    select c.ItemId;

var conditionalCountQuery = 
    from c in conditionalChecksQuery
    group c by c.ItemId into cGrouped
    select new { ItemId = cGrouped.Key, NumTrue = cGrouped.Count() };

var itemResultQuery = 
    from c in conditionalCountQuery
    join i in db.Items on c.ItemId equals i.Id
    select new { Item = i, NumTrue = c.NumTrue };

var finalQuery =
    from result in itemResultQuery
    where result.NumTrue == 2
    select result;

Answer 2

我认为这样的事情应该有效

Select * FROM (
    Select c.ItemID, Count(*) As NumTrue
    FROM ConditionalProperties c, Properties p
    WHERE c.PropertyId = p.Id AND c.IsChecked = 1 AND (
    (p.SystemName = 'eatable') OR
    (p.SystemName = 'diy')
    GROUP BY ItemID
) AS ConditionalCount 
INNER JOIN Items AS I
ON  ConditionalCount.ItemID = I.id
WHERE ConditionalCount.NumTrue = 2

这是SQL，不知道为什么我认为你在做LINQ，并且想要SQL，但这是一种更简单的SQL形式，应该与你的多个查询完全相同。

可以将此SQL转换为LINQ吗？

2 个答案: