下面假设有一张sc表,保存学生选课记录,有课程号,学号,平时分,卷面分,总分。
建立数据库表过程:
create table class(
cno varchar(8) not null,
sno varchar(8) not null,
ordinary_score int,
last_score int,
all_score int
);
存储过程
由括号包围的参数列必须总是存在。如果没有参数,也该使用一个空参数列()。每个参数 默认都是一个IN参数。要指定为其它参数,可在参数名之前使用关键词IN(默认,可缺省) OUT或INOUT。
IN参数是只传入
OUT参数是只传出
INOUT参数是既传入又传入,即双向传递
指定参数为IN, OUT, 或INOUT 只对PROCEDURE是合法的。(FUNCTION参数总是被认为是IN参数)
建立存储过程,传入平时分x,卷面分y,平时分所占的比率pert,学号,课程号;建立过程如下
- delimiter //
- CREATE PROCEDURE cal_grade(x INT,y INT,out t int,pert float,s VARCHAR(8),c VARCHAR(8))
- LABEL_PROC:
- BEGIN
- IF ( x < 0 || x > 100 ) THEN
- SET t = -1;
- LEAVE LABEL_PROC;
- END IF;
- IF ( y < 0 || y > 100 ) THEN
- SET t = -2;
- LEAVE LABEL_PROC;
- END IF;
- SET t = ROUND( x*pert + y*(1-pert) );
- UPDATE sc SET ordinary_score=x,last_score=y WHERE sno=s AND cno=c AND tno=tn;
- END LABEL_PROC //
- delimiter ;
- #include <stdio.h>
- #include "mysql.h"
- int main()
- {
- MYSQL *my_connection;
- MYSQL_RES *res_ptr;
- MYSQL_ROW sqlrow;
- char buf[100];
- my_connection = mysql_init (NULL);
- //下面连接的最后一个参数必须为CLIENT_MULTI_STATEMENTS,不然就会报错select error: PROCEDURE *** can’t return a result set in the given context
- my_connection = mysql_real_connect (my_connection, "localhost", "root", "root", "test", 0, NULL, CLIENT_MULTI_STATEMENTS);
- sprintf (buf, "call cal_grade(%d,%d,@t,%f,%s,%s)", 10, 10, 0.3, 123, 456);
- if ( mysql_query (my_connection, buf) )
- sprintf (stderr, mysql_error (my_connection));
- else
- {
- //获得返回参数@t,@t是传出参数
- mysql_query (my_connection, "select @t");
- res_ptr = mysql_store_result (my_connection);
- if (res_ptr)
- {
- sqlrow = mysql_fetch_row (res_ptr);
- if (!strcmp (sqlrow[0], "-1"))
- printf ("平时分不在范围之内\n");
- else if (!strcmp (sqlrow[0], "-2"))
- printf ("卷面分不在范围之内\n");
- else
- printf ("总分为:%s\n", sqlrow[0]);
- }
- mysql_free_result (res_ptr);
- }
- mysql_close (my_connection);
- return 0;
- }
来源: http://www.phpxs.com/code/1004057/