The heart of SQL in a relational system is the ability to perform relational joins. Joins are specified by using more than one table name in the FROM clause of a query. A joined table specifies an intermediate result table that is the result of either an inner join or an outer join.
The maximum number of tables that can be coded in a single FROM clause is 15, but there can be up to 225 table references in an SQL statement. The 15 table limit can be increased by updating the macro SPRMMXT to a value greater than 15. Also, the 15 table limit does not apply to star join queries.
The join operation used most often is the one we ...