mysql> drop procedure if exists `addAge` $$
Query OK, 0 rows affected (0.00 sec)

mysql> create procedure addAge(age int,fun varchar(10))
    -> begin
    -> if fun='add' then 
    -> 	select 'add';
    -> else
    -> 	select 'j';
    -> end if;
    -> end $$
Query OK, 0 rows affected (0.00 sec)

mysql> call addAge(10,"add")$$
+-----+
| add |
+-----+
| add |
+-----+
1 row in set (0.00 sec)

Query OK, 0 rows affected (0.00 sec)

mysql> call addAge(10,"jian")$$
+---+
| j |
+---+
| j |
+---+
1 row in set (0.00 sec)

Query OK, 0 rows affected (0.00 sec)

mysql> show tables $$
+----------------+
| Tables_in_test |
+----------------+
| web_stu        |
| web_student    |
+----------------+
2 rows in set (0.00 sec)

mysql> select * from web_stu $$
+--------+
| sex    |
+--------+
| male   |
| female |
+--------+
2 rows in set (0.01 sec)

mysql> select * from web_student $$
+----+----------+------+------------+
| id | username | age  | posttime   |
+----+----------+------+------------+
|  1 | d3aAB6   |   65 | 1478144500 |
|  2 | lTaQ5h   |   55 | 1478144505 |
|  3 | uBFpCW   |   40 | 1478144509 |
|  4 | KeELzx   |   42 | 1478144534 |
|  5 | 1uHRl5   |   39 | 1478158277 |
+----+----------+------+------------+
5 rows in set (0.00 sec)

mysql> create procedure p3(n int)
    ->  select  * from web_student where cid > n;
    -> end $$
Query OK, 0 rows affected (0.00 sec)

mysql> create procedure p3(n int)
    -> begin
    ->  select  * from web_student where cid > n;
    -> end $$
ERROR 1304 (42000): PROCEDURE p3 already exists
mysql> drop procedure if exists `p3` $$
Query OK, 0 rows affected (0.00 sec)

mysql> create procedure p3(n int)
    -> begin
    ->  select  * from web_student where cid > n;
    -> end $$
Query OK, 0 rows affected (0.00 sec)

mysql> call p3(3)$$
ERROR 1054 (42S22): Unknown column 'cid' in 'where clause'
mysql> drop procedure if exists `p3` $$
Query OK, 0 rows affected (0.00 sec)

mysql> create procedure p3(n int)
    -> begin
    ->  select  * from web_student where id > n;
    -> end $$
Query OK, 0 rows affected (0.00 sec)

mysql> call p3(3)$$
+----+----------+------+------------+
| id | username | age  | posttime   |
+----+----------+------+------------+
|  4 | KeELzx   |   42 | 1478144534 |
|  5 | 1uHRl5   |   39 | 1478158277 |
+----+----------+------+------------+
2 rows in set (0.00 sec)

Query OK, 0 rows affected (0.02 sec)

mysql> exit $$