Database Reference
In-Depth Information
4.14.4 Equi-Join
The join operator takes two relations as input and produces one relation as output.
In Equi-Join two tables are combined together but only for records where the values
match in the join columns of two tables. The equi-join operator is a product with an
associated restrict. We shall assume that the primary key of one table and the foreign
key of the other table form the default join columns.
Syntax is:
EQUIJOIN <table1> WITH <table2><result table>
Example 14:
EQUIJOIN Teacher WITH Module R
Here we have joined Teacher and Module, but only produced a row in R where a Teacher
table TeacherID value matches a module table TeacherID value.
4.14.5 Natural Join
