Question

What is the result of the following SQL query?

Union
SELECT lname, hrly_wage, 'poor' FROM hourly WHERE hrly_wage ≤ 15
union
SELECT lname, hrly_wage, 'okay' FROM hourly WHERE hrly_wage > 15

Answer 1

The given SQL query uses the UNION operator to combine the results of two SELECT statements. It selects lname, hrly_wage, and a string literal based on the value of hrly_wage. The final result will contain all the selected columns from both SELECT statements.

Step-by-step explanation:

The given SQL query combines the results of two SELECT statements using the UNION operator. The first SELECT statement selects lname, hrly_wage, and 'poor' as a string literal from the hourly table where hrly_wage is less than or equal to 15. The second SELECT statement selects lname, hrly_wage, and 'okay' as a string literal from the hourly table where hrly_wage is greater than 15.

The UNION operator concatenates the result sets of both SELECT statements, removing any duplicate rows, to produce the final result. The result will contain all the columns selected in each SELECT statement.

For example, if the first SELECT statement returns the rows ('John', 10.5, 'poor') and ('Karen', 14.75, 'poor'), and the second SELECT statement returns the rows ('Tom', 16.25, 'okay') and ('Emily', 20.5, 'okay'), then the result of the UNION operation will be:

[('John', 10.5, 'poor'), ('Karen', 14.75, 'poor'), ('Tom', 16.25, 'okay'), ('Emily', 20.5, 'okay')]