Union

Question 1

What does the UNION set operator do?

Answer 1

It appends tables together.

Last Revised: 4/2/21, 5.3

Question 2

When using the UNION set operator, where does it go?

Answer 2

Between the two SELECT statements you would like to append.

Last Revised: 4/2/21, 5.6

Question 3

What are the three requirements of the columns in the SELECT clauses in order for the UNION set operator to work?

Answer 3

1. There must be the same number of columns
2. The columns must be in the same order
3. The columns must have similar data types, respectively

(Last Revised: 4/2/21, 5.7)

Question 4

TRUE or FALSE: When using the UNION set operator, the resulting table uses the column names supplied in the second SELECT clause.

Answer 4

False
The resulting table uses the column names supplied in the first SELECT clause.

(Last Revised: 4/2/21, 5.8)

Question 5

The UNION set operator returns only distinct values by default. How would you allow duplicate values?

Answer 5

By using UNION ALL

Last Revised: 4/2/21, 5.8