MySQL 自定义函数CREATE FUNCTION示例

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)