Question

Which of the following describes how to append tables?
A) Put each table in its own SELECT statement, then put UNION or UNION ALL between SELECT statements
B) Put each table in its own FROM clause, then put UNION or UNION ALL between FROM clauses.
C) List tables after the Keyword UNION or UNION ALL, separated by commas.
D) Start with UNION ( ) and list tables inside the parentheses, separated by commas, optionally followed by ALL.

Answer 1

Append tables:

• Put each table in its own SELECT statement, then put UNION or UNION ALL between SELECT statements.
• UNION and UNION ALL purpose is combine results.

Example:

select eid,ename from Employee UNION select customerId,customerName from customer.

	eid	ename
1	530	sandeep
2	545	Raj

	cid	cname
1	530	sandeep
2	533	Ravj

Output:

	cid	cname
1	530	sandeep
2	545	Raj
3	533	Ravj