Q: What is a self-join?
A: A self-join is a standard SQL Server join that joins a table to itself. You can perform a self-join when all the data you require is in a single table, and the data you need to extract relates to other data in the same table. You join a table to itself using a field or combination of fields that have matching data in different records. To perform a self-join, you must use a table name for each instance of the table, so...