An error is produced because you cannot create a TEMPORARY TABLE with a UNION.

The employees common to both tables exist in employees MAIN.

A unique list of employees exist in employeesMAIN.

All rows from both tables exist in employeesMAIN.

‘Casper’ and ‘ undefined values are inserted into the ‘name’ and gender’ column.

The server returns an error indicating that ‘undefined’ cannot be inserted into a column of ENUM type

The server returns a warning and the empty string is inserted to the ‘gender’ column.

The server returns a warning and the first specified value ,”male” is inserted to the gender column.

SELECT DISTINCT last_name, first_name FROM people

SELECT 1,2 FROM people GROUP BY last_name

SELECT first_name, last _name FROM people WHERE age LIKE ‘2’

SELECT 1, 2 FROM people WHERE last _name =’smith’

SELECT first _name, last_name FROM people LIMIT 1, 2