Relational database stored procedure

1. Definitions: stored procedure is a set of pre-compiled set sql statement.
2. Benefits: improve reusability, reduce redundancy, reduce the number of compilation sql, reducing the number of connections to interact with the server.

3. syntax to create a stored procedure

The CREATE  PROCEDURE stored procedure name (parameter list)
 the BEGIN 
    body of the procedure; 
the END

4. The parameter list consists of three parts: parameter mode (in / out / in ~ out), the parameter name, parameter type

Parameter Mode:
　　in: incoming caller needs, similar to the parameter java
　　out: as the return value, similar to the java return
　　in ~ out: the parameters passed by the caller, may return a value corresponding to
if only the body of the procedure then the corresponding sentence may be omitted begin end;
the end of each one of the body of the procedure sql statement must semicolon;
ending delimiter flag stored procedure required to re-set the mark stored procedure.

5. call a stored procedure

CALL stored procedure name (arguments);

6. Case

Build employee table, department table, role table

Reference # Empty configured 
DELIMITER $ 
the CREATE PROCEDURE ADD1 () 
the BEGIN 
	the SELECT 'the SD'; 
the END $ 
the CALL RADD ();

#带IN 模式的存储过程
#通过部门名称查询对应的员工信息
DELIMITER $
CREATE PROCEDURE empinfo(IN dept_name varchar(20))
BEGIN
	SELECT
		e.e_id,
		e.e_name,
		d.dept_name
	FROM
		employee e RIGHT JOIN department d
	ON
		e.dept_id=d.dept_id
	WHERE
		d.dept_name=dept_name;
END $

CALL empinfo('开发部')

#通过员工部门名称和角色信息，查询员工是否存在，如果存在则显示存在两字，否则显示不存在
DELIMITER $
CREATE PROCEDURE empinfo1(IN dept_name VARCHAR(20),IN r_name VARCHAR(20))
BEGIN
		DECLARE result int DEFAULT 0;
		SELECT count(*) INTO result FROM emoloyee e
		LEFT JOIN department d
		ON e.dept_id=d.dept_id
		LEFT JOIN role r
		ON r.r_id=e.r_id
		WHERE d.dept_name=dept_name AND r.r_name=r_name;
		SELECT 
			IF(result>0,'存在','不存在');
END $
CALL emploinfo1('开发部','一级管理员');

#带out的存储过程
#传入员工姓名显示对应的部门名称
DELIMITER $
CREATE PROCEDURE empdep(IN empName VARCHAR(20),OUT deptName VARCHAR(20))
BEGIN
	SELECT 
		d.dept_name INTO deptName
	FROM 
		employee e LEFT JOIN department d
	ON
		e.dept_id=d.dept_id
	WHERE
		e.e_name=empName;
END $
#调用
CALL empdep('据',@DeptName);
SELECT @DeptName;

#通过员工姓名返回员工对应的部门名称和角色名称
CREATE PROCEDURE deptNameAndRoleName(IN emp_name VARCHAR(10),OUT dep_name VARCHAR(20),OUT rol_name VARCHAR(20))
BEGIN
	SELECT d.dept_name 部门名称,r.r_name 角色名称 INTO dep_name,rol_name
	FROM employee e
	LEFT JOIN department d
	ON d.dept_id=e.dept_id
	LEFT JOIN role r
	ON r.r_name=e.r_name
	WHERE
		e.e_name=emp_name
END $

#调用
CALL deptNameAndRoleName('hjbj',@deptNAME,@ROLEnaME)

#查看变量
SELECT @deptNAME,@ROLEnaME;

#创建IN~OUT
#传入对应的工资计算年薪
DELIMITER $
CREATE PROCEDURE salaryss(INOUT s1 DOUBLE,INOUT s2 DOUBLE)
BEGIN
	SET s1=s1*12;
	SET s2=s2*12;
END 
#调用
set @s1=1000;
set @s2=1200;
CALL salaryss(@s1,@s2);
SELECT @s1,@s2

　7.删除存储过程(一次只能删除一个)

DROP PROCEDURE 存储过程名;

　8.查看存储过程

SHOW CREATE PROCEDURE 存储过程名

　9.修改存储过程（一般创建好不允许修改）

Relational database stored procedure

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