What is an Outer Join?
An outer join extends the result of a simple join. An outer join returns all rows that satisfy the join condition and those rows from one table for which no rows from the other satisfy the join condition. Such rows are not returned by a simple join. To write a query that performs an outer join of tables A and B and returns all rows from A, apply the outer join operator (+) to all columns of B in the join condition. For all rows in A that have no matching rows in B, Oracle returns null for any select list expressions containing columns of B. Outer join queries are subject to the following rules and restrictions:vThe (+) operator can appear only in the WHERE clause or, in the context of left correlation (that is, when specifying the TABLE clause) in the FROM clause, and can be applied only to a column of a table or view.vIf A and B are joined by multiple join conditions, you must use the (+) operator in all of these conditions. If you do not, Oracle will return only the rows resulting fr
