Opposite of inner join

Question

What will be the opposite of inner join? For a table table Person (int PersonId, varchar PersoName, int AddrId), I want to know the rows in Person with bad Ad

Answer 1

An Inner join is not diametric to an Outer Join. They serve different purposes. However, a common pattern to find rows from one table that do not exist in another is to use an Outer Join:

Select ...
From Table1
    Left Join Table2
        On Table2.ForeignKeyCol = Table1.PrimaryKeyCol
Where Table2.PrimaryKeyCol Is Null

This returns all rows from Table1 and any matching rows from Table2 such that if a given Table1 row has no Table2 match, a null for the Table2 columns are returned. By then requiring that a non-nullable column (Table2.PrimaryKeyCol) be Null, I will get all rows from Table1 that do not exist in Table2. Using your example table names we would have something like:

Select ...
From Person
    Left Join Address
        On Address.PersonId = Person.Id
Where Address.Id Is Null