在LINQ查询中，我是否可以或应该将两个Where子句连接起来？

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问题描述

我有以下课程:

public partial class Content
{
    public int ContentId { get; set; }
    public int ContentTypeId { get; set; }
    public string Title { get; set; }
    public string Text { get; set; }

    public int SubjectId { get; set; }
    public virtual Subject Subject { get; set; }
}

我知道我可以使用这样的 Linq 查询:

.Where(a => a.SubjectId == subjectId)

但是我怎样才能使它有另一个条件

.Where(a => a.ContentTypeId == contentTypId)

有没有一种方法可以将它们合并为一个，或者它们应该保持为两个?

推荐答案

只使用一个包含所有条件的 Where 子句:

.Where(a => a.SubjectId == subjectId && a.ContentTypeId == contentTypId)

或两个 Where 子句，每个处理一个条件:

.Where(a => a.SubjectId == subjectId)
.Where(a => a.ContentTypeId == contentTypId)

是等价的，因为 LINQ 查询执行被推迟到结果调用.

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问题描述

I have the following class:

public partial class Content
{
    public int ContentId { get; set; }
    public int ContentTypeId { get; set; }
    public string Title { get; set; }
    public string Text { get; set; }

    public int SubjectId { get; set; }
    public virtual Subject Subject { get; set; }
}

I understand I can use a Linq query like this:

.Where(a => a.SubjectId == subjectId)

However how can I make it so there is another condition

.Where(a => a.ContentTypeId == contentTypId)

is there a way I can join these into one where or should they remain as two?

推荐答案

Using only one Where clause containing every condition:

.Where(a => a.SubjectId == subjectId && a.ContentTypeId == contentTypId)

Or two Where clauses, dealing with one condition each:

.Where(a => a.SubjectId == subjectId)
.Where(a => a.ContentTypeId == contentTypId)

is equivalent, as the LINQ query execution is deferred until the call to the result.

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