在LINQ to SQL中检索单个记录结果的最佳方法 [英] Best way for retrieving single record results in LINQ to SQL

问题描述

如果我查询键字段中具有条件的表，如:

If I query a table with a condition on the key field as in:

        var user = from u in dc.Users
                   where u.UserName == usn
                   select u;

我知道我将得到零个结果或一个结果.我还是应该继续使用for-each检索结果，还是有另一种首选的方式来处理这种情况?

I know that I will either get zero results or one result. Should I still go ahead and retrieve the results using a for-each or is there another preferred way to handle this kind of situation.

推荐答案

尝试如下操作:

var user = (from u in dc.Users
                   where u.UserName == usn
                   select u).FirstOrDefault();

FirstOrDefault 方法返回满足条件的序列的第一个元素指定条件或默认值(如果找不到此类元素).

The FirstOrDefault method returns the first element of a sequence that satisfies a specified condition or a default value if no such element is found.

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