MySQL, create a simple function [closed]

Answer 1

Try to change CREATE FUNCTION F_TEST(PID INT) RETURNS VARCHAR this portion to CREATE FUNCTION F_TEST(PID INT) RETURNS TEXT

and change the following line too.

DECLARE NAME_FOUND TEXT DEFAULT "";

It should work.

Answer 2

MySQL function example:

Open the mysql terminal:

el@apollo:~$ mysql -u root -pthepassword yourdb
mysql>

Drop the function if it already exists

mysql> drop function if exists myfunc;
Query OK, 0 rows affected, 1 warning (0.00 sec)

Create the function

mysql> create function hello(id INT)
    -> returns CHAR(50)
    -> return 'foobar';
Query OK, 0 rows affected (0.01 sec)

Create a simple table to test it out with

mysql> create table yar (id INT);
Query OK, 0 rows affected (0.07 sec)

Insert three values into the table yar

mysql> insert into yar values(5), (7), (9);
Query OK, 3 rows affected (0.04 sec)
Records: 3  Duplicates: 0  Warnings: 0

Select all the values from yar, run our function hello each time:

mysql> select id, hello(5) from yar;
+------+----------+
| id   | hello(5) |
+------+----------+
|    5 | foobar   |
|    7 | foobar   |
|    9 | foobar   |
+------+----------+
3 rows in set (0.01 sec)

Verbalize and internalize what just happened:

You created a function called hello which takes one parameter. The parameter is ignored and returns a CHAR(50) containing the value 'foobar'. You created a table called yar and added three rows to it. The select statement runs the function hello(5) for each row returned by yar.

Answer 3

this is a mysql function example. I hope it helps. (I have not tested it yet, but should work)

DROP FUNCTION IF EXISTS F_TEST //
CREATE FUNCTION F_TEST(PID INT) RETURNS VARCHAR
BEGIN
/*DECLARE VALUES YOU MAY NEED, EXAMPLE:
  DECLARE NOM_VAR1 DATATYPE [DEFAULT] VALUE;
  */
  DECLARE NAME_FOUND VARCHAR DEFAULT "";

    SELECT EMPLOYEE_NAME INTO NAME_FOUND FROM TABLE_NAME WHERE ID = PID;
  RETURN NAME_FOUND;
END;//