Question

A union combines the rows from two or more what?

a. SELECT statements
b. result tables
c. queries
d. all of the above

Answer 1

A union combines the rows from two or more SELECT statements. The UNION operator in SQL is used to combine the result sets of multiple SELECT statements into a single result set.

Step-by-step explanation:

A union combines the rows from two or more SELECT statements. In a SQL query, the UNION operator is used to combine the result sets of two or more SELECT statements into a single result set. This allows you to retrieve data from multiple tables or views in a single query.

For example:

SELECT column1, column2 FROM table1
UNION
SELECT column1, column2 FROM table2;

This query combines the rows from table1 and table2, and returns a result set with the selected columns.