mysql sql语句使用变量

DELIMITER //

CREATE PROCEDURE GetEmployeeByDepartment(IN deptName VARCHAR(255))
BEGIN
    DECLARE empName VARCHAR(255);
    DECLARE done INT DEFAULT FALSE;

    DECLARE cur CURSOR FOR SELECT name FROM employees WHERE department = deptName;
    DECLARE CONTINUE HANDLER FOR NOT FOUND SET done = TRUE;

    OPEN cur;

    read_loop: LOOP
        FETCH cur INTO empName;
        IF done THEN
            LEAVE read_loop;
        END IF;
        SELECT empName;
    END LOOP;

    CLOSE cur;
END //

DELIMITER ;

SET @myVariable = 'someValue';

DELIMITER //

CREATE PROCEDURE TestVariableScope()
BEGIN
    DECLARE localVar INT DEFAULT 10;
    SET @globalVar = 20;

    SELECT localVar, @globalVar;
END //

DELIMITER ;

SET @myInt = 123; -- 正确
SET @myInt = '123'; -- 错误，字符串不能赋值给整数变量