How to use SQL 'LIKE' with LINQ to Entities? [duplicate]

Answer 1

We use Database First and the EntityFramework.

The "Map your own function." approach works for us together with the nuget EntityFramework.CodeFirstStoreFunctions.

1 Step: Create a function in the db like this:

CREATE FUNCTION [dbo].[StringLike]
(
      @a nvarchar(4000),
      @b nvarchar(4000)
)
RETURNS bit
AS
BEGIN
    RETURN 
    (SELECT CASE
            WHEN (SELECT 1 WHERE @a LIKE @b) = 1 THEN 1
            ELSE 0
            END)  
END

2 Step: Install nuget EntityFramework.CodeFirstStoreFunctions

3 Step: Create a method in your code like this (I create mine in the DbContext class):

[DbFunction("CodeFirstDatabaseSchema", "StringLike")]
public static bool Like(string input, string pattern)
{
    throw new NotSupportedException("Direct calls are not supported.");
}

4 Step: Initalize EntityFramework.CodeFirstStoreFunctions.

protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
    modelBuilder.Conventions.Add(new FunctionsConvention("dbo", this.GetType()));
}

5 Step: Now you can use this method in your linq query.

Answer 2

the solution is to use SQLFunctions.PatIndex

var result = from c in items
             where SqlFunctions.PatIndex(searchstring.ToLower(), c.fieldtoSearch) > 0
             select c;

where 'searchstring' is the pattern to search 'fieldtoSearch' is the field to search

Patindex() supports search using string pattern search. The search is case insensitive.

Answer 3

var people = from t in entities.People
                 where t.Name.ToLower().Contains(searchTerm.ToLower())
                 select new { t.Name };

EDIT- I might be mixing syntax. I usually use extension methods; but contains will work.

Answer 4

http://social.msdn.microsoft.com/Forums/en-US/adodotnetentityframework/thread/6529a35b-6629-44fb-8ea4-3a44d232d6b9/

var people = entities.People.Where("it.Name LIKE @searchTerm", new ObjectParameter("searchTerm", searchTerm));

Answer 5

You can do this:

using System.Data.Entity;  // EntityFramework.dll v4.3
var queryResult=db.Accounts.AsQueryable().Where(x => x.Name.Contains(queryKey));

because Linq to Entity can't transform the method Contains() to the SQL, but Linq to SQL can do this. I tried to find a method that can doing a cast, at last, AsQueryable(), also a generic version AsQueryable<T>(). I found I can do this using it this way in my case, but any side effect it has I don't know, maybe it will lose some feature at Entity.