Question

I have a screen in my project ” Enquiry” where I user can perform 2 kinds of search.I cannot figure out how to do a “like” or “And or is null” in Linq to entity.

1. Simple Search ( Search in all fields using “Like” operator)
2. Advanced Advanced Search (Use “And” Operator)

So lets take these 3 tables and make up a noddy example.

1. Customer Table (CustomerID,Name,Surname)
2. Address(AddressID,Street,City)
3. CustomerOrder (OrderID,OrderName)

Basic search :
this is how I would do it in Sql

  SELECT TOP (100) C.Name,C.Surname,CA.Street,CA.City,CO.OrderName
  FROM Customer C 
  LEFT JOIN CustomerAddress CA ON C.CustomerID=CA.CustomerID
  LEFT JOIN CustomerOrders CO ON C.CustomerID=CA.CustomerID   
  WHERE  (C.CustomerID LIKE '%' + @SearchText + '%'  
  OR C.Surname LIKE '%' + @SearchText + '%' 
  OR C.Name LIKE '%' + @SearchText + '%'        
  OR CA.Street LIKE '%' + @SearchText + '%'
  OR CA.City LIKE '%' + @SearchText + '%'
  OR  CO.OrderName LIKE '%' + @SearchText + '%') )

Advanced Search

This my sql where clause

    WHERE  (C.CustomerID =@CustomerID or @CustomerID ISNULL  
    AND C.Surname =@Surname or @Surname ISNULL
    AND C.Name=@Name or @Name ISNULL        
    AND CA.Street =@Street or @Street ISNULL
    AND CA.City =@City or @City ISNULL
    AND  CO.OrderName =@OrderName or @OrderName ISNULL)
    AND ((ModifiedDate BETWEEN ISNULL(convert(varchar,@FromDate,101),'01/01/1901')
    AND ISNULL(convert(varchar,@ToDate,101),'12/31/9999'))

How do you do Likes or and or is null in entity framework?

thanks a lot!

Answer 1

For LIKE, you can use Contains, StartsWith, or EndsWith. For IS NULL, use == null.

Example:

var list = from p in Products
           where (p.Description.Contains("v") && p.Description.StartsWith("C"))
                    || p.MFRCode == "TOYOTA"
                    || p.Universal == null                   
           select p;

will cause EF to generate this SQL:

SELECT 
[Extent1].[MFRCode] AS [MFRCode], 
[Extent1].[MFRProductID] AS [MFRProductID], 
[Extent1].[Universal] AS [Universal], 
[Extent1].[Description] AS [Description]
FROM [dbo].[Products] AS [Extent1]
WHERE (([Extent1].[Description] LIKE N'%v%') AND ([Extent1].[Description] LIKE N'C%')) OR (N'TOYOTA' = [Extent1].[MFRCode]) OR ([Extent1].[Universal] IS NULL)

and produce these results:

Edit

I used LINQPad to generate these results. It’s a great tool, free to use (there’s an option to purchase an Intellisense feature), and definitely worth a look if you’d like to experiment with different LINQ queries and see the SQL that EF is generating (it’s good for general LINQ experimentation and quickly trying out simple code as well).