如何在EF5中使用“ SELECT IN”

Question

我发送了这个罕见的查询，我真的很难将其传递给ef，能否请我帮忙？

提前非常感谢你

SELECT
    c.*
FROM
    Company c
    JOIN [User] u ON c.id = u.id_company
WHERE
    (
        ( u.id_usertype = 3 )
        AND
        ( u.id = 2135 )
    )

UNION

SELECT
    c.*
FROM
    Company c
    JOIN Company mc ON c.id_company = mc.id
WHERE
    mc.id in
    (
        SELECT
            c.id
        FROM
            Company c
            JOIN [User] u ON c.id = u.id_company 
        WHERE
        (
            ( u.id_usertype = 3 )
            AND
            ( u.id = 2135 )
        )
    )

Answer 1

现在，您已经解释了子公司/公司的关系，我看到可以将查询更改为以下查询：

SELECT
    Company.*
FROM
    [User]
    INNER JOIN Company ON [User].id_company = Company.id
WHERE
    [User].id = 2135

UNION

SELECT
    SubCompany .*
FROM
    [User]
    INNER JOIN Company ON [User].id_company = Company.id
    INNER JOIN Company AS SubCompany ON Company.id = SubCompany.id_company
WHERE
    [User].id = 2135

通过更改INNER JOIN Company As SubCompany ，可以将基于UNION的查询简化为以下单个查询，以便使用OR使其既与原始公司也与子公司匹配。

SELECT
    SubCompany.*
FROM
    [User]
    INNER JOIN Company ON [User].id_company = Company.id
    LEFT OUTER JOIN Company AS SubCompany ON
    (
        Company.id = SubCompany.id_company
        OR
        Company.id = SubCompany.id
    )
WHERE
    [User].id = 2135

但是，在Linq中，如果使用的是Navigation Properties，则不能使用复杂的JOIN条件（如果使用Linq的GroupBy或Join操作，则可以使用），因此，我们必须通过Concat操作退回到UNION ：

我假设您在实体框架中定义了Company->SubCompany关系，在这种情况下，可以使用SelectMany ：

var query = dbContext
    .Users
    .Where( u => u.id == 2135 )
    .Select( u => u.Company )
    .Concat(
        dbContext
            .Users
            .Where( u => u.id == 2135 )
            .SelectMany( u => u.Company.SubCompanies )
    );