MySQL Tutorial/Procedure Function/Call

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Call another function

   <source lang="sql">

mysql> mysql> delimiter $$ mysql> mysql> CREATE FUNCTION isodd(input_number int)

   ->        RETURNS int
   -> BEGIN
   ->         DECLARE v_isodd INT;
   ->
   ->         IF MOD(input_number,2)=0 THEN
   ->                 SET v_isodd=FALSE;
   ->         ELSE
   ->                 SET v_isodd=TRUE;
   ->         END IF;
   ->
   ->         RETURN(v_isodd);
   ->
   -> END$$

Query OK, 0 rows affected (0.01 sec) mysql> mysql> CREATE PROCEDURE myProc(aNumber int)

   -> Begin
   ->      IF (isodd(aNumber)) THEN
   ->           SELECT " is odd";
   ->      ELSE
   ->           SELECT " is even";
   ->      END IF;
   -> END$$

Query OK, 0 rows affected (0.02 sec) mysql> mysql> delimiter ; mysql> mysql> mysql> call myProc(2); +----------+ | is even | +----------+ | is even | +----------+ 1 row in set (0.00 sec) Query OK, 0 rows affected (0.01 sec) mysql> mysql> call myProc(1); +---------+ | is odd | +---------+ | is odd | +---------+ 1 row in set (0.00 sec) Query OK, 0 rows affected (0.00 sec) mysql> mysql> call myProc(4); +----------+ | is even | +----------+ | is even | +----------+ 1 row in set (0.00 sec) Query OK, 0 rows affected (0.00 sec) mysql> mysql> mysql> drop procedure myProc; Query OK, 0 rows affected (0.00 sec) mysql> drop function isodd; Query OK, 0 rows affected (0.00 sec) mysql> mysql></source>


Call another procedure

From the MySQL client, you use the CALL statement to execute a procedure, providing the procedure name and correct number of arguments.



   <source lang="sql">

CALL [database.]<procedure name> ([<parameter>, <parameter>, -]);</source>


Call another procedure to pass the error code

   <source lang="sql">

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

   ->      MODIFIES SQL DATA
   -> BEGIN
   ->      DECLARE l_status VARCHAR(20);
   ->
   ->     CALL myProc1(l_status);
   ->        IF l_status="Duplicate Entry" THEN
   ->               SELECT CONCAT("Warning: using existing definition for location ") AS warning;
   ->      END IF;
   -> END$$

Query OK, 0 rows affected (0.00 sec) mysql> mysql> CREATE PROCEDURE myProc1(OUT out_status VARCHAR(30))

   -> BEGIN
   ->    set out_status = "Duplicate Entry";
   -> END$$

Query OK, 0 rows affected (0.00 sec) mysql> mysql> mysql> delimiter ; mysql> call myProc(); +--------------------------------------------------+ | warning | +--------------------------------------------------+ | Warning: using existing definition for location | +--------------------------------------------------+ 1 row in set (0.00 sec) Query OK, 0 rows affected (0.01 sec) mysql> drop procedure myProc; Query OK, 0 rows affected (0.00 sec) mysql> drop procedure myProc1; Query OK, 0 rows affected (0.00 sec) mysql> mysql></source>


Call another procedure with parameter

   <source lang="sql">

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

   -> BEGIN
   ->
   ->      SELECT "in proc"+ id;
   -> END$$

Query OK, 0 rows affected (0.00 sec) mysql> mysql> CREATE PROCEDURE myProc1()

   -> BEGIN
   ->
   ->      call myProc(1);
   -> END$$

Query OK, 0 rows affected (0.00 sec) mysql> mysql> delimiter ; mysql> mysql> call myProc1(); +---------------+ | "in proc"+ id | +---------------+ | 1 | +---------------+ 1 row in set (0.00 sec) Query OK, 0 rows affected, 1 warning (0.02 sec) mysql> mysql> drop procedure myProc; Query OK, 0 rows affected (0.00 sec) mysql> drop procedure myProc1; Query OK, 0 rows affected (0.00 sec) mysql></source>


CALL Statement Syntax

   <source lang="sql">

CALL sp_name([parameter[,...]])

  CALL sp_name[()]</source>
   
  

The CALL statement invokes a procedure.

CALL can pass back values to its caller.

A client program can call the ROW_COUNT() function to get the count of affected rows.

Nested function call

   <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 (0.02 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> mysql> delimiter $$ mysql> mysql> CREATE FUNCTION myFunction(in_rep_id INT)

   ->      RETURNS INT
   ->      READS SQL DATA
   -> BEGIN
   ->      DECLARE customer_count INT;
   ->
   ->      SELECT COUNT(*)
   ->           INTO customer_count
   ->        FROM employee
   ->       WHERE id=in_rep_id;
   ->
   ->      RETURN(customer_count);
   ->
   -> END$$

Query OK, 0 rows affected (0.00 sec) mysql> mysql> mysql> CREATE PROCEDURE myProc(in_employee_id INT)

   -> BEGIN
   ->     IF myFunction(in_employee_id) > 0 THEN
   ->           select "greater than 0";
   ->     ELSE
   ->           select "less or equals than 0";
   ->     END IF;
   -> END$$

Query OK, 0 rows affected (0.00 sec) mysql> mysql> delimiter ; mysql> mysql> call myProc(1); +----------------+ | greater than 0 | +----------------+ | greater than 0 | +----------------+ 1 row in set (0.02 sec) Query OK, 0 rows affected (0.02 sec) mysql> mysql> drop function myFunction; Query OK, 0 rows affected (0.00 sec) mysql> drop procedure myProc; Query OK, 0 rows affected (0.00 sec) mysql> mysql> mysql> mysql> mysql> drop table Employee; Query OK, 0 rows affected (0.00 sec) mysql> mysql></source>