MySQL 存储过程关于调用

Question

I am new in programming and this is my first question in the forum. Can you explain me please in this code in MySQL why I get the result 3? I thought I would get 2. If I run again it increases every time by one. Thank you.

DELIMITER $$
CREATE PROCEDURE uservariable()
BEGIN
SET @x = @x + 1;
SELECT @x;
END$$

SET @x = 1;
CALL uservariable();
CALL uservariable();

Answer 1

SET @x = @x + 1;

This line increments @x value by one each time uservariable() procedure is called.

SET @x = 1; --@x value is 1 
CALL uservariable(); --@x value is 2
CALL uservariable(); --@x value is 3