Database Reference
In-Depth Information
will produce all Teachers who are not administrators
Teacher ID Teacher Name
102 Aman Kumar
103 Nigam
Designation
Sr. Lecturer Lecturer
Administrator DIFFERENCE Teacher R will show rows from administrator table who
are not Teachers
4.14.9 Division
Division or divide takes two tables as input and produces one table as output.
One of the input tables must be a binary table (i.e. a table with two columns). The other
input table must be a unary table (i.e. a table with one column). The unary table must
also be defined on the same domain as one of the columns in the binary table. The
fundamental idea of division is that we take the values of the unary table and check
them off against the associated column in the binary table. Whenever all the values in
the unary table match with the same value in the binary table then we output a value to
the output table.
Example 19:
Suppose that we maintain a table( ModuleDay) with a list of days on which
particular modules are taught:
