How can I correct the correlation names on this sql join?

Question

I need a join that yields three fields with the same name from two different tables. When I try to run my sql query, VS gives me the following error.

Answer 1

Use table aliases for each reference to PoliticalFigures instead:

SELECT 
  Countries.Name AS Country, 
  P.Name AS President, 
  VP.Name AS VicePresident
FROM
  Countries
  LEFT OUTER JOIN PoliticalFigures AS P ON Countries.President_Id = P.Id
  LEFT OUTER JOIN PoliticalFigures AS VP ON Countries.VicePresident_Id = VP.Id

Answer 2

Give each reference to the table an alias:

SELECT
    Countries.Name AS Country,
    P.Name AS President,
    VP.Name AS VicePresident
FROM Countries
LEFT JOIN PoliticalFigures P ON Countries.President_Id = P.Id
LEFT JOIN PoliticalFigures VP ON Countries.VicePresident_Id = VP.Id

Answer 3

In the SQL Standards, the vernacular 'table alias' is referred to as a correlation name and the vernacular 'column alias' is referred to as an as clause. It seems you have the two terms confused.

Answer 4

You need to use AS on the tables to give them aliases:

SELECT Countries.Name AS Country, Pres.Name AS President, Vice.Name AS VicePresident FROM Countries
LEFT OUTER JOIN PoliticalFigures AS Pres ON Countries.President_Id = Pres.Id
LEFT OUTER JOIN PoliticalFigures AS Vice ON Countries.VicePresident_Id = Vice.Id