grade表:

select * from grade;
+----+------+--------+------+-------+-------+
| id | name | sexy   | age  | score | class |
+----+------+--------+------+-------+-------+
|  1 | a    | male   |   15 |    90 | A(1)  |
|  2 | b    | male   |   13 |    97 | A(1)  |
|  3 | c    | female |   15 |    79 | A(2
 
)  |
|  4 | a    | female |   13 |   100 | B(1)  |
|  5 | d    | male   |   16 |    89 | B(2)  |
|  6 | e    | male   |   16 |    97 | B(2)  |
|  7 | f    | female |   15 |    93 | B(3)  |
|  8 | g    | female |   13 |    88 | C(1)  |
|  9 | h    | male   |   14 |    91 | C(2)  |
+----+------+--------+------+-------+-------+
 

創建存儲過程p_grade

delimiter &&
create procedure p_grade(in g_id int,out g_name varchar(20))
begin
declare g_score varchar(20);
select score into g_score from grade where id = g_id;
select name into g_name from grade where id = g_id;
select g_score;
end
&&
delimiter ;

call p_grade(1,@n
 
);
+---------+
| g_score |
+---------+
| 90      |
+---------+

select @n;
+------+
| @n   |
+------+
| a    |
+------+

1.參數g_name的作用範圍是begin...end之間

2.declare聲明的變量作用範圍是begin...end之間

3.declare必須在所有set前面，即使是變量g_name,也必須在所有declare之後賦值。

4.declare可以聲明多個變量，但是多個變量的類型必須一致。

　　正確語法:declare a,b,c int default 10;

　　錯誤語法: declare a int,b int,c int;

5.sql語句中為了給g_score和g_name賦值，使用了兩條select語句。簡潔寫法如下

　　select score,name into g_score,g_name from grade where id = g_id;

存儲過程和存儲函數