How to perform a LEFT JOIN in SQL Server between two SELECT statements?

Question

I have two SELECT statements in SQL Server like these:

(SELECT [UserID] FROM [User]) (SELECT [TailUser], [Weight] FROM [Edge] WHERE [HeadUser] = 5043) 

I want to perform a LEFT JOIN between these two SELECT statements on [UserID] attribute and [TailUser] attribute. I want to join existent records in second query with the corresponding records in first query and NULL value for absent records. How can I do this?

Answer 1

SELECT * FROM  (SELECT [UserID] FROM [User]) a LEFT JOIN (SELECT [TailUser], [Weight] FROM [Edge] WHERE [HeadUser] = 5043) b ON a.UserId = b.TailUser