MySQL Tutorial/Procedure Function/Buildin Functions

Call buildin math function in your procedure

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>

Check MySQL version

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>

Return the file size by using the LOAD_FILE function

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>

Use Build-in SUM function in a procedure

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>

Using String functions in a user-defined function

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>