Introduction and basic use of stored procedures

• Catalog

  Introduce

  benefits ：

  The difference between stored procedures and functions ( Almost no difference )

  Create and call stored procedures

  Create stored procedure

  Calling stored procedure

  Examples demonstrate

  Data preparation

  Create and call stored procedures

  View and delete of stored procedures

  View all stored procedures in the database

  Delete stored procedure

  Example operation

  ---

• Introduce

• Stored procedures and functions are compiled in advance and stored in the database a section SQL Collection of statements

• benefits ：

• Improve code reusability
• Reduce data transfer between database and application server , Increase of efficiency
• ( For databases , Later, it should be defined on one or more servers , Transmission later will definitely affect efficiency )
• Reduce business processing at the code level

• The difference between stored procedures and functions ( Almost no difference )

• The storage function must have a return value
• A stored procedure may not return a value

• Create and call stored procedures

• Create stored procedure

• -- Modify the end separator
• delimiter $
• -- Create stored procedure
• create procedure Stored procedure name ( parameter list )
• begin
• SQL Statement list
• end$
• -- Modify the end separator
• delimiter ;

• Calling stored procedure

• call Stored procedure name ( The actual parameter )

• Examples demonstrate

• Data preparation

• 
• 

• --  Create student table 
  CREATE TABLE student(
    id INT PRIMARY KEY auto_increment, --  Student id
  	name VARCHAR(20), --  The student's name 
  	age INT, --  Student age 
  	gender VARCHAR(5), --  Student gender 
  	score INT --  Student achievement 
  );
  --  Add data 
  INSERT INTO student VALUES (NULL,' Zhang San ',23,' male ',95),(NULL,' Li Si ',24,' male ',98),(NULL,' Wang Wu ',25,' Woman ',100),(NULL,' Zhao Liu ',26,' Woman ',90);

• Create and call stored procedures

• 

• --  establish stu_group() stored procedure , encapsulation   Group query total score , And sort in ascending order according to the total score 
  delimiter $
  CREATE PROCEDURE stu_group()
  BEGIN
      SELECT gender,SUM(score) getsum FROM student GROUP BY gender ORDER BY getsum ASC;
  END$
  delimiter ;

• 

• --  call stu_group() stored procedure 
  CALL stu_group;

• View and delete of stored procedures

• View all stored procedures in the database

• select * from mysql.proc where db=' Database name '

• Delete stored procedure

• drop procedure [if exists] Stored procedure name

• Example operation

• 

• --  see dp1 All stored procedures in the database 
  SELECT * FROM mysql.proc WHERE db='dp1';

• 

• --  Delete stored procedure 
  DROP PROCEDURE IF EXISTS stu_group;