Chapter 15_ Stored Procedures and Stored Functions

#第15章_储存过程与存储函数

#1创建存储过程
#举例1：
CREATE DATABASE dbtest15;
USE dbtest15;
CREATE TABLE employess
AS
SELECT * 
FROM atguigudb.`employees`;
CREATE TABLE departments
AS
SELECT * 
FROM atguigudb.`departments`;
SELECT * FROM employess;
SELECT * FROM departments;

DELIMITER $
CREATE PROCEDURE select_all_data()
BEGIN
	SELECT * FROM employess;
END $
DELIMITER ;

#2.存储过程的调用：
CALL select_all_data();


DELIMITER $
CREATE PROCEDURE show_max_salary()
BEGIN 
		SELECT MAX(salary)
		FROM employess;
END $

DELIMITER ;

CALL show_max_salary();

#；类型2：带OUT
DELIMITER $
CREATE PROCEDURE show_min_salary(OUT ms DOUBLE)
BEGIN
SELECT MIN(salary) INTO ms
FROM employess;
END$
DELIMITER ;

CALL show_min_salary(@ms);

SELECT @ms;

#in
DELIMITER $
CREATE PROCEDURE show_someone_salary(IN empname VARCHAR(20))
BEGIN
SELECT salary 
FROM employess
WHERE last_name = empname;
END$
DELIMITER ;
#调用方式1：
CALL show_someone_salary('Abel');
#调用方式2：
SET @empname = 'Abel';


#in  和  out
DELIMITER $
CREATE PROCEDURE show_someone_salary2(IN empname VARCHAR(20),OUT empsalary DECIMAL(10,2))
BEGIN
SELECT salary INTO empsalary
FROM employess
WHERE last_name = empname;
END$
DELIMITER ;

#调用
SET @empname = 'Abel';
CALL show_someone_salary2(@empname,@empsalary);

SELECT @empsalary;


#inout
DELIMITER $
CREATE PROCEDURE show_mgr_name(INOUT empname VARCHAR(25))
BEGIN
	SELECT e2.last_name INTO empname
	FROM employess e1 JOIN employess e2
	ON e1.manager_id = e2.employee_id
	WHERE e1.last_name = empname;
END$
DELIMITER ;
SET @empname = 'Abel';
CALL show_mgr_name(@empname);
SELECT @empname;


#2.存储函数：
DELIMITER $

CREATE FUNCTION email_by_name()
RETURNS VARCHAR(25)
	DETERMINISTIC
	CONTAINS SQL
	READS SQL DATA 
BEGIN
	RETURN (SELECT email FROM employess WHERE last_name = 'Abel'); 
END $

DELIMITER ;
#调用：
SELECT email_by_name();


#3.存储过程的查看情况
#3.1
SHOW CREATE PROCEDURE show_mgr_name;

SHOW CREATE FUNCTION 
#3.2
SHOW PROCEDURE STATUS;
SHOW PROCEDURE STATUS LIKE 'show_mgr_name';#模糊查询

#3.3

#4.函数的修改