SQL中创建存储过程

CREATE PROCEDURE p_student_select()
BEGIN 
SELECT * FROM student;
END

CALL p_student_select()

# out其实就是cpp里的引用变量，in就是值传递
CREATE PROCEDURE p_count(OUT count int)
BEGIN
SELECT COUNT(*) into count FROM student;
END

set @num = 10;	# 定义变量
CALL p_count(@num);		#我的数据有11条
SELECT @num as num;		#这里的num已经是11了

--这个就是一个调用参数的函数
CREATE PROCEDURE p_studnt_selectById(in id int)
BEGIN
SELECT * FROM student WHERE studentNo = id;
END

CALL p_studnt_selectById(4)

#两个参数是一样的用法
CREATE PROCEDURE p_result_test(out num int, in id int)
BEGIN
SELECT COUNT(*) INTO num FROM result WHERE studentNo = id;
END

set @num = 0;
CALL p_result_test(@num, 3);
SELECT @num as num

# declare的作用是用来定义变量

CREATE PROCEDURE p5()
BEGIN
DECLARE studentName VARCHAR(10);	#创建了一个变量
set @studentName = 'HELLO';		#给变量赋值
END

CALL p5();
SELECT @studentName
-- 说明了declare定义的变量可以在外部直接调用

#if语句没啥说的，代码直接能看懂
CREATE PROCEDURE p6(in id int)
BEGIN
IF(id = 0) THEN
	SELECT * FROM student;
ELSE
	SELECT * FROM teacher;
END IF;
END

#看代码...
CREATE PROCEDURE p7(in tab VARCHAR(10))
BEGIN
CASE tab
	WHEN 'student' THEN
		SELECT * FROM student;
	WHEN 'teacher' THEN
		SELECT * FROM teacher;
END CASE;
END

CREATE PROCEDURE p9(IN id INT)
BEGIN
addloop: LOOP
	set id = id + 1;
	SELECT id;
	IF id > 10 THEN
		LEAVE addloop;
	ELSE
		SELECT * FROM student; 
	END IF; 
END LOOP addloop;

END

CREATE PROCEDURE p10(in count int)
BEGIN
REPEAT
	set count = count + 1;
	SELECT count;
UNTIL count > 10 END REPEAT;	#count >10跳出

END

CREATE PROCEDURE p11(in num int)
BEGIN
while num < 10 DO
	SELECT num;
	SET  num = num + 1; 
END WHILE;
END