本文介绍了包含多列查询的处理方法,对大家解决问题具有一定的参考价值,需要的朋友们下面随着小编来一起学习吧!
问题描述
当任一列可能为空时,如何使用LINQ to SQL搜索多个列?
How do I search multiple columns using LINQ to SQL when any one of the column could be null?
IEnumerable<User> users = from user in databaseUsers where user.ScreenName.Contains(search) || user.FirstName.Contains(search) || user.LastName.Contains(search) select user;我不断收到此异常:
对象引用未设置为 对象的实例.
Object reference not set to an instance of an object.
说明:一个 期间发生未处理的异常 当前网站的执行情况 要求.请检查堆栈跟踪 有关该错误的更多信息 以及它在代码中的起源.
Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.
异常详细信息: System.NullReferenceException:对象 引用未设置为的实例 一个对象.
Exception Details: System.NullReferenceException: Object reference not set to an instance of an object.
推荐答案
添加非空条件user.Property != null
IEnumerable<User> users = from user in databaseUsers where (user.ScreenName != null && user.ScreenName.Contains(search)) || (user.FirstName != null && user.FirstName.Contains(search)) || ( user.LastName != null && user.LastName.Contains(search)) select user;更多推荐
包含多列查询
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