转换SQL包含对Entity Framework的查询

Question

I am currently converting some SQL to C# code against Entity Framework and have come up against an issue with a keyword search query.

The (very) simplified query ultimately looks like this:

SELECT * FROM SomeTable
WHERE CONTAINS(Col1, Col2, Col3, '"word"')

As per the docs https://docs.microsoft.com/en-us/sql/t-sql/queries/contains-transact-sql this method searches for fuzzy or precise matches on words or phrases. So if I ran a search for the keyword of "word" I will get results where Col1, Col2 or Col3 have the instance of "word".

I have tried writing a string contains method against Entity Framework:

Context.Where(i => i.Col1.Contains("word") || i.Col2.Contains("word") || i.Col3.Contains("word"))

However this produces a wildcard like query '%word%' and returns results that are not relevant, for example I get matches on "word" and "swords".

How would I be able to get the same results as the SQL contains query?

Answer 1

You have to write a custom SQL function and call this one from C#.

For example:

CREATE FUNCTION [dbo].[Search](@Search nvarchar(4000))
RETURNS TABLE
AS
RETURN (
    SELECT 
        *
    FROM 
        [dbo].[SomeTable]
    WHERE 
        CONTAINS(Col1, Col2, Col3, @Search)
)
GO

When it is generated to EDMX use it like this

var query = this.DataContext.Search("my search string");

Answer 2

Try Using SqlMethods.Like

Example:

Context.Where(x=> SqlMethods.Like(x.Col1,'word') 
||SqlMethods.Like(x.Col2,'word')).ToList();

You can find SqlMethods Under System.Data.Linq.SqlClient;