Union, Intercept, Except

Question 1

What does the Union Statement do?

Answer 1

The UNION keyword combines the results of two SELECT statements into a single result set, eliminating duplicate rows by default.

Question 2

What defines the column
name used in the result set?

Answer 2

The first data set entered into SQL.

Question 3

What two things must the data sets have if you want to use the union keyword?

Answer 3

Datasets must have the same number of columns and similar datatypes.

Question 4

What’s the difference between UNION and UNION ALL?

Answer 4

UNION ALL UNION ALL will
leave the duplicate rows in the result set. Their queries will also execute faster because it does not check for duplicate values.

Question 5

What does INTERSECT do?

Answer 5

The INTERSECT keyword returns distinct rows that are found in both datasets.

Question 6

How many data sets can be compared with the INTERSECT keyword?

Answer 6

2 datasets

Question 7

What does the EXCEPT keyword do?

Answer 7

The EXCEPT keyword returns rows from the first dataset that are not found in the second dataset