MySQL Tutorial/Procedure Function/Buildin Functions

Call buildin math function in your procedure

   <source lang="sql">

mysql> delimiter $$ mysql> mysql> mysql> CREATE PROCEDURE myProc()

   -> BEGIN
   ->     DECLARE my_big_integer     int DEFAULT 2;
   ->
   ->     SET my_big_integer=POWER(my_big_integer,3);
   ->
   ->     select my_big_integer;
   -> END$$

Query OK, 0 rows affected (0.00 sec) mysql> delimiter ; mysql> mysql> call myProc(); +----------------+ | my_big_integer | +----------------+ | 8 | +----------------+ 1 row in set (0.00 sec) Query OK, 0 rows affected (0.00 sec) mysql> drop procedure myProc; Query OK, 0 rows affected (0.00 sec) mysql> mysql></source>

Check MySQL version

   <source lang="sql">

mysql> mysql> delimiter $$ mysql> mysql> mysql> CREATE PROCEDURE myProc()

   -> BEGIN
   ->
   ->   IF (CAST(SUBSTR(version(),1,3) AS DECIMAL(2,1)) <5.0) THEN
   ->     SELECT "MySQL versions earlier than 5.0";
   ->   ELSE
   ->     SELECT "Thank you are running 5.0 or higher!";
   ->   END IF;
   ->
   -> END$$

Query OK, 0 rows affected (0.02 sec) mysql> mysql> delimiter ; mysql> call myProc(); +--------------------------------------+ | Thank you are running 5.0 or higher! | +--------------------------------------+ | Thank you are running 5.0 or higher! | +--------------------------------------+ 1 row in set (0.00 sec) Query OK, 0 rows affected (0.02 sec) mysql> drop procedure myProc; Query OK, 0 rows affected (0.00 sec) mysql></source>

Return the file size by using the LOAD_FILE function

   <source lang="sql">

mysql> mysql> delimiter $$ mysql> mysql> CREATE PROCEDURE filesize(in_file_name VARCHAR(128))

   ->
   -> BEGIN
   ->   DECLARE mytext TEXT;
   ->   SET mytext=LOAD_FILE(in_file_name);
   ->   SELECT in_file_name||" contains "||length(mytext)||" bytes"
   ->       AS output;
   -> END$$

Query OK, 0 rows affected (0.00 sec) mysql> mysql> delimiter ; mysql> call filesize("a.txt"); +--------+ | output | +--------+ | NULL | +--------+ 1 row in set (0.00 sec) Query OK, 0 rows affected, 2 warnings (0.00 sec) mysql> drop procedure filesize; Query OK, 0 rows affected (0.00 sec) mysql> mysql></source>

Use Build-in SUM function in a procedure

   <source lang="sql">

mysql> mysql> CREATE TABLE Employee(

   ->     id            int,
   ->     first_name    VARCHAR(15),
   ->     last_name     VARCHAR(15),
   ->     start_date    DATE,
   ->     end_date      DATE,
   ->     salary        FLOAT(8,2),
   ->     city          VARCHAR(10),
   ->     description   VARCHAR(15)
   -> );

Query OK, 0 rows affected (0.03 sec) mysql> mysql> mysql> insert into Employee(id,first_name, last_name, start_date, end_Date, salary, City, Description)

   ->              values (1,"Jason",    "Martin",  "19960725",  "20060725", 1234.56, "Toronto",  "Programmer");

Query OK, 1 row affected (0.00 sec) mysql> mysql> insert into Employee(id,first_name, last_name, start_date, end_Date, salary, City, Description)

   ->               values(2,"Alison",   "Mathews",  "19760321", "19860221", 6661.78, "Vancouver","Tester");

Query OK, 1 row affected (0.00 sec) mysql> mysql> insert into Employee(id,first_name, last_name, start_date, end_Date, salary, City, Description)

   ->               values(3,"James",    "Smith",    "19781212", "19900315", 6544.78, "Vancouver","Tester");

Query OK, 1 row affected (0.00 sec) mysql> mysql> insert into Employee(id,first_name, last_name, start_date, end_Date, salary, City, Description)

   ->               values(4,"Celia",    "Rice",     "19821024", "19990421", 2344.78, "Vancouver","Manager");

Query OK, 1 row affected (0.00 sec) mysql> mysql> insert into Employee(id,first_name, last_name, start_date, end_Date, salary, City, Description)

   ->               values(5,"Robert",   "Black",    "19840115", "19980808", 2334.78, "Vancouver","Tester");

Query OK, 1 row affected (0.00 sec) mysql> mysql> insert into Employee(id,first_name, last_name, start_date, end_Date, salary, City, Description)

   ->               values(6,"Linda",    "Green",    "19870730", "19960104", 4322.78,"New York",  "Tester");

Query OK, 1 row affected (0.00 sec) mysql> mysql> insert into Employee(id,first_name, last_name, start_date, end_Date, salary, City, Description)

   ->               values(7,"David",    "Larry",    "19901231", "19980212", 7897.78,"New York",  "Manager");

Query OK, 1 row affected (0.00 sec) mysql> mysql> insert into Employee(id,first_name, last_name, start_date, end_Date, salary, City, Description)

   ->               values(8,"James",    "Cat",     "19960917",  "20020415", 1232.78,"Vancouver", "Tester");

Query OK, 1 row affected (0.00 sec) mysql> mysql> select * from Employee; +------+------------+-----------+------------+------------+---------+-----------+-------------+ | id | first_name | last_name | start_date | end_date | salary | city | description | +------+------------+-----------+------------+------------+---------+-----------+-------------+ | 1 | Jason | Martin | 1996-07-25 | 2006-07-25 | 1234.56 | Toronto | Programmer | | 2 | Alison | Mathews | 1976-03-21 | 1986-02-21 | 6661.78 | Vancouver | Tester | | 3 | James | Smith | 1978-12-12 | 1990-03-15 | 6544.78 | Vancouver | Tester | | 4 | Celia | Rice | 1982-10-24 | 1999-04-21 | 2344.78 | Vancouver | Manager | | 5 | Robert | Black | 1984-01-15 | 1998-08-08 | 2334.78 | Vancouver | Tester | | 6 | Linda | Green | 1987-07-30 | 1996-01-04 | 4322.78 | New York | Tester | | 7 | David | Larry | 1990-12-31 | 1998-02-12 | 7897.78 | New York | Manager | | 8 | James | Cat | 1996-09-17 | 2002-04-15 | 1232.78 | Vancouver | Tester | +------+------------+-----------+------------+------------+---------+-----------+-------------+ 8 rows in set (0.00 sec) mysql> mysql> mysql> delimiter $$ mysql> CREATE PROCEDURE myProc(in_id INT)

   -> READS SQL DATA
   -> BEGIN
   ->     DECLARE total_salary NUMERIC(8,2);
   ->
   ->     SELECT SUM(salary)
   ->       INTO total_salary
   ->       FROM employee
   ->      WHERE id=in_id;
   ->
   ->     SELECT CONCAT("Total salary ",in_id," is ",total_salary);
   -> END$$

Query OK, 0 rows affected (0.00 sec) mysql> mysql> mysql> delimiter ; mysql> mysql> call myProc(3); +---------------------------------------------------+ | CONCAT("Total salary ",in_id," is ",total_salary) | +---------------------------------------------------+ | Total salary 3 is 6544.78 | +---------------------------------------------------+ 1 row in set (0.00 sec) Query OK, 0 rows affected, 1 warning (0.00 sec) mysql> DROP PROCEDURE myProc; Query OK, 0 rows affected (0.02 sec) mysql> mysql> mysql> mysql> mysql> drop table Employee; Query OK, 0 rows affected (0.00 sec) mysql> mysql></source>

Using String functions in a user-defined function

   <source lang="sql">

mysql> mysql> delimiter $$ mysql> mysql> CREATE FUNCTION myFunction

   ->    (in_string      VARCHAR(255),
   ->     in_find_str    VARCHAR(20),
   ->     in_repl_str    VARCHAR(20))
   ->
   ->   RETURNS VARCHAR(255)
   -> BEGIN
   ->   DECLARE l_new_string VARCHAR(255);
   ->   DECLARE l_find_pos   INT;
   ->
   ->   SET l_find_pos=INSTR(in_string,in_find_str);
   ->
   ->   IF (l_find_pos>0) THEN
   ->     SET l_new_string=INSERT(in_string,l_find_pos,LENGTH(in_find_str),in_repl_str);
   ->   ELSE
   ->     SET l_new_string=in_string;
   ->   END IF;
   ->   RETURN(l_new_string);
   ->
   -> END$$

Query OK, 0 rows affected (0.00 sec) mysql> mysql> delimiter ; mysql> select myFunction("ABC","A","Z"); +---------------------------+ | myFunction("ABC","A","Z") | +---------------------------+ | ZBC | +---------------------------+ 1 row in set (0.00 sec) mysql> drop function myFunction; Query OK, 0 rows affected (0.00 sec) mysql> mysql></source>