UNION: Exercises

• Create an address list for all employees, customer contacts, and supplier contacts, sorted by name. For this exercise, use employee's last name only.

• Change the previous query to use the employee's last name and first name. (More than one way to do this.)

• Change one of the previous queries to include an additional column (call it Role) where each person is designated as Employee, Customer, or Supplier.

SYNTAX

• Without duplication:

SELECT statement1

UNION

SELECT statement2

UNION

[...]

SELECT statement-last

ORDER BY column list

• To include all rows, regardless of duplication:

SELECT statement1

UNION ALL

[...]

SELECT statement-last

ORDER BY column list

Other set operators (Oracle): INTERSECT and MINUS