A self-join is a query in which a table is joined (compared) to itself. Self-joins are used to compare values in a column with other values in the same column in the same table. One practical use for self-joins: obtaining running counts and running totals in an SQL query.

Simply we can say join means join and self join means A table join with itself i.e called Self Join.

Joining to iteself is nothing but self join. Ex: Empno Mgr 1 2 2 3 3 4 In the above for empno 1, empno 2 is manager. To extract this type of data we use self joins.

a table join with it self is called as self join

A self join involves a relationship with only one table.

A self join can be of any type, as long as the joined tables are the same. A self join is rather unique in that it involves a relationship with only one table.