LINQ to Entities使用表达式树生成的SQL语句比较

👤 dnawo 📅 2014-12-25 👁 3026 👍 0 💬 0 🔄 来源：本站原创

不使用表达式树：

var query = context.People.Where(item => item.Age == 20);

Select
[Extent1].[Id] AS [Id],
[Extent1].[Name] AS [Name],
[Extent1].[Age] AS [Age]
FROM [dbo].[Person] AS [Extent1]
Where 20 = [Extent1].[Age]

使用表达式树：

Expression<Func<Person, bool>> exp = item => item.Age == 20;
var query = context.People.Where(exp.Compile());

Select
[Extent1].[Id] AS [Id],
[Extent1].[Name] AS [Name],
[Extent1].[Age] AS [Age]
FROM [dbo].[Person] AS [Extent1]

结论：使用表达式树生成的SQL语句不包含查询条件，这样返回的记录比不使用表达式树时多。

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