MySQL Tutorial/Procedure Function/Call

Call another function

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>

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.

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

Call another procedure to pass the error code

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>

Call another procedure with parameter

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>

CALL Statement Syntax

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

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

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>