MySql 100104：Connector/C
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MySql 100104：Connector/C
@
http://zcatt.cublog.cn
1．框架
基本步骤：
a) mysql_library_init()
b)mysql_init()
c) Issue SQL statements and process their
results
d) mysql_close()
e) mysql_library_end()
The client can send SQL statement to the
server using mysql_query() or mysql_real_query() The diff is that mysql_query()
expects the query to be specified as a null-terminated string whereas
mysql_real_query() expects a counted string.
If the string contains binary data(which may include null bytes), you
must use mysql_real_query().
For SELECT queries, mysql_store_result()
get all the row returned from the server and stores them in the client. And
mysql_use_result() initiates a row-by-row result set, but does not actually get
any rows from the server. In both
cases, you access rows by calling mysql_fetch_row().
After you are done with a result set, call
mysql_free_result() to free the memory used for it.
if using mysql_store_result, you can move
back and forth in the result set by using mysql_data_seek() or
mysql_row_seek(), and you can also find out how many rows there are by calling
mysql_num_rows().
2．主要函数
id
func
Description
1
mysql_library_init()
初始化mysql
library. 对于mysql单线程场景，可以忽略，mysql_init()默认会调用这个函数。对于多线程场景，应当在起始时调用。
2
mysql_library_end()
对应mysql_library_end()，建议调用。
3
mysql_init()
初始化MYSQL结构，
4
mysql_real_connect()
给定host,
user, passwd, port，dbname等，连接mysql server。注意不应当再使用过期的mysql_connect()
5
mysql_close()
关闭连接。
6
mysql_store_result()
查询结果集合全部取回client
7
mysql_use_result()
一行一行的取回查询结果集合
8
mysql_free_result()
释放结果集合占用的内存
9
mysql_fetch_row()
取结果集合中的下一行
10
mysql_errno()
错误码
11
mysql_error()
错误信息
3．例子
预备条件：
server上的账户 root:passwd@localhost:3306, 数据库是world, 其中的表city结构如下
mysql> desc
city;
+-------------+----------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+-------------+----------+------+-----+---------+----------------+
| ID | int(11)| NO
| PRI | NULL | auto_increment |
| Name | char(35) | NO |
| | |
| CountryCode |
char(3)| NO |
| | |
| District | char(20) | NO |
| | |
|
Population| int(11)| NO
| | 0 | |
+-------------+----------+------+-----+---------+----------------+
5 rows in set
(0.00 sec)
程序如下
// mysqlTest.cpp : 定义控制台应用程序的入口点。
//
#include "stdafx.h"
#include "mysql.h"
#define MYSQL_PORT 3306
#define MYSQL_HOST "localhost"
#define MYSQL_USER "root"
#define MYSQL_PASSWD "passwd"
#define MYSQL_DB "world"
#define MYSQL_SELECTSTATEMENT "select id, name, countrycode from city"
MYSQL mySQLHandler;
int _tmain(int argc, _TCHAR* argv[])
{
unsigned
int r;
MYSQL_RES *mySQLRes;
MYSQL_ROW mySQLRow;
mysql_library_init(0,NULL,NULL);
mysql_init(&mySQLHandler);
printf("1.
inited ---------------\n");
if
(!mysql_real_connect(&mySQLHandler, MYSQL_HOST, MYSQL_USER, MYSQL_PASSWD,
MYSQL_DB,MYSQL_PORT, NULL, 0))
{
printf( "Error connecting to database: %s\n",mysql_error(&mySQLHandler));
return
1;
}
printf("2.
connected ---------------\n");
r =
mysql_real_query(&mySQLHandler, MYSQL_SELECTSTATEMENT, (unsigned long)
strlen(MYSQL_SELECTSTATEMENT));
if(r)
{
printf( "query err: %s\n",mysql_error(&mySQLHandler));
return
1;
}
printf("3.queried
---------------\n");
mySQLRes = mysql_store_result(&mySQLHandler);
if
(!mySQLRes)
{
printf( "store result err: %s\n",mysql_error(&mySQLHandler));
return
1;
}
printf("3.stored
result ---------------\n");
while(mySQLRow
= mysql_fetch_row(mySQLRes))
{
for(r=0;r
{
printf("%s ",mySQLRow);
}
printf("\n");
}
printf("4.fetched
rows ---------------\n");
mysql_free_result(mySQLRes);
printf("5.free
result ---------------\n");
mysql_close(&mySQLHandler);
printf("6.close
mysql ---------------\n");
// mysql_library_end();
return
0;
}
本文来自ChinaUnix博客，如果查看原文请点：http://blog.chinaunix.net/u/8866/showart_2139333.html
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