LINQ to Entities无法识别方法'Int32 IndexOf(System.String，System.StringComparison)'方法 [英] LINQ to Entities does not recognize the method 'Int32 IndexOf(System.String, System.StringComparison)' method

问题描述

我已经通过使用如下所示的Entityframework执行了linq查询

I have executed a linq query by using Entityframework like below

GroupMaster getGroup = null;
getGroup = DataContext.Groups.FirstOrDefault(item => keyword.IndexOf(item.Keywords,StringComparison.OrdinalIgnoreCase)>=0 && item.IsEnabled)

执行此方法时，出现如下异常

when executing this method I got exception like below

LINQ to Entities无法识别方法'Int32 IndexOf(System.String，System.StringComparison)'方法，并且 方法不能转换为商店表达式.

LINQ to Entities does not recognize the method 'Int32 IndexOf(System.String, System.StringComparison)' method, and this method cannot be translated into a store expression.

默认情况下，Contains()方法区分大小写，因此再次需要转换为小写.除了contains方法外，是否有任何方法可以检查字符串是否匹配?是否有任何方法可以解决indexOf方法问题?

Contains() method by default case sensitive so again I need to convert to lower.Is there any method for checking a string match other than the contains method and is there any method to solve the indexOf method issue?

推荐答案

您这里实际上只有四个选项.

You really only have four options here.

1. 全局更改数据库的排序规则.这可以通过多种方式完成，一个简单的Google搜索就可以显示它们.
2. 更改单个表或列的排序规则.
3. 使用存储过程并在查询中指定COLATE语句
4. 执行查询并返回大量结果，然后使用Linq to Objects在内存中进行过滤.

除非您的结果集很小，否则

数字4不是一个好的选择. #3如果您不能更改数据库(但不能与它一起使用Linq)则很好.

number 4 is not a good option unless your result set is pretty small. #3 is good if you can't change the database (but you can't use Linq with it).

数字1和2是您需要对整个数据模型进行选择的选择，或者仅在特定字段上进行选择.

numbers 1 and 2 are choices you need to make about your data model as a whole, or if you only want to do it on specific fields.

更改服务器排序规则: http://technet.microsoft.com/en-us/library/ms179254.aspx

Changing the Servers collation: http://technet.microsoft.com/en-us/library/ms179254.aspx

更改数据库排序规则: http://technet.microsoft.com/en-us/library/ms179254.aspx

Changing the Database Collation: http://technet.microsoft.com/en-us/library/ms179254.aspx

更改列排序规则: http://technet.microsoft.com/en -us/library/ms190920(v = sql.105).aspx

在存储的proc中使用Collat​​e语句: http://technet.microsoft.com/en-us/library/ms184391.aspx

Using the Collate statement in a stored proc: http://technet.microsoft.com/en-us/library/ms184391.aspx

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