set variable and select mysql code example

Example 1: how to put value in variable mysql

SET variable = (SELECT SUM(tax) FROM taxable_transactions);

Example 2: define a variable in mysql from select

SELECT salary INTO @variable1 FROM employee_info WHERE emp_id = 12345678 LIMIT 1;
SELECT salary, salary_group INTO @var1, @var2 FROM employee_info WHERE emp_id = 12345678;