创建SQL存储过程需要使用到的语法
- 创建存储过程
CREATE 存储过程的名称(参数)
BEGIN
...需要执行的SQL语句
END- 调用
CALL 存储过程的名称(参数)个人看法，这就是一个函数...

无参数

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

带参

# 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;
ENDset @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;
ENDCALL p_studnt_selectById(4)

两个参数

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

declare关键字的使用

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

IF语句

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

case语句

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

loop语句

CREATE PROCEDURE p9(IN id INT)
BEGIN
addloop: LOOPset id = id + 1;SELECT id;IF id > 10 THENLEAVE addloop;ELSESELECT * FROM student; END IF; 
END LOOP addloop;END

repeat

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

while

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