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.