if条件语句mysql

IF condition THEN
    statement_list;
[ELSEIF condition THEN]
    statement_list;
[ELSE]
    statement_list;
END IF;

DELIMITER //

CREATE PROCEDURE UpdateEmployeeLevel()
BEGIN
    DECLARE emp_id INT;
    DECLARE emp_salary DECIMAL(10, 2);
    DECLARE emp_level VARCHAR(20);

    -- 假设我们有一个游标来遍历 employees 表
    DECLARE cur CURSOR FOR SELECT id, salary FROM employees;
    OPEN cur;

    read_loop: LOOP
        FETCH cur INTO emp_id, emp_salary;
        IF emp_salary < 3000 THEN
            SET emp_level = '初级';
        ELSEIF emp_salary < 6000 THEN
            SET emp_level = '中级';
        ELSE
            SET emp_level = '高级';
        END IF;

        -- 更新员工的等级
        UPDATE employees SET level = emp_level WHERE id = emp_id;
    END LOOP;

    CLOSE cur;
END //

DELIMITER ;