Discussion on: Using C# LINQ API to perform SQL IN logic at WHERE clause

[Alex Ruzenhack]

Here is the EF SQL of "Users":

Microsoft.EntityFrameworkCore.Database.Command:Information: Executed DbCommand (110ms) [Parameters=[], CommandType='Text', CommandTimeout='30']
SELECT [user].[Id], [user].[Email], [user].[CustomerId], [user].[UserName]
FROM [AspNetUsers] AS [user]
WHERE [user].[CustomerId] IS NULL

And here is the EF SQL of "Customers":

Microsoft.EntityFrameworkCore.Database.Command:Information: Executed DbCommand (16ms) [Parameters=[], CommandType='Text', CommandTimeout='30']
SELECT [t].[Id], [t].[Email], [t].[FullName], [t].[RegisteredAt],  [t].[CreatedAt], [t].[UpdatedAt]
FROM [Customers] AS [t]

As we can see, the IN logic really occurs in memory.

[Sung M. Kim]

Thanks for the clarification Alex 😎