c連接mysql的實(shí)例

odin_free

今天給新來(lái)的同事做mysql培訓(xùn)，用到的一個(gè)例子：
連接數(shù)據(jù)庫(kù)test 用戶名root密碼abc
在里面有一個(gè)username的表，describe username結(jié)果如下
mysql> describe username;
+----------+-------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+----------+-------------+------+-----+---------+-------+
| id | int(10) | YES | | NULL | |
| username | varchar(32) | | PRI | | |
+----------+-------------+------+-----+---------+-------+
mysql> select * from username;
+------+----------+
| id | username |
+------+----------+
| 1 | sfs |
+------+----------+
1 row in set (0.00 sec)
本文目的查找執(zhí)行select id from username這個(gè)語(yǔ)句并打印結(jié)果
代碼:
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
MYSQL mysql;
main()
{
   char host[32]="localhost";
   char user[32]="root";
   char passwd[32]="abc";
   char dbname[32]="test";   
   
   if( mysql_init(&mysql) == NULL )
   {
      syslog(LOG_USER|LOG_INFO,"inital mysql handle errorn");
      return 1;
   }
   if (mysql_real_connect(&mysql,host,user,passwd,dbname,0,NULL,0) == NULL)
   {
      syslog(LOG_USER|LOG_INFO, "Failed to connect to database: Error: %sn",mysql_error(&mysql));
      return 1;
   }
   else syslog(LOG_USER|LOG_INFO, "connect to database: n");
   find_ps();   
   db_close();
   return 0;
}
int db_close()
{
        mysql_close(&mysql);
         return 0;
}
int  find_ps ()
{
   MYSQL_ROW m_row;
   MYSQL_RES *m_res;
   char sql[1024],username[32];
   int res=1;
   int *id;
   sprintf(sql,"select id from username");
   if(mysql_query(&mysql,sql) != 0)
   {
      syslog(LOG_USER|LOG_INFO, "select ps_info Error: %sn",mysql_error(&mysql));
      return res;
   }
   m_res = mysql_store_result(&mysql);
   if(m_res==NULL)
   {
      syslog(LOG_USER|LOG_INFO, "select username Error: %sn",mysql_error(&mysql));
      res = 3;
      return res;
   }
   if(m_row = mysql_fetch_row(m_res))
   {
      printf("m_row=%dn",atoi(m_row[0]));
      res = 0;      
   }
   mysql_free_result(m_res);
   return res;
}
編譯命令
gcc -g connect_db.c -L/usr/lib/mysql -lmysqlclient -lz
注意：
如果/tmp/ccTGmMS21.o: In function `main':
/tmp/ccTGmMS21.o(.text+0x11): undefined reference to `mysql_init'
那么參數(shù)增加-L/usr/lib/mysql -lmysqlclient
如果
usr/lib/mysql/libmysqlclient.a(my_compress.o): In function `my_uncompress':
my_compress.o(.text+0xaa): undefined reference to `uncompress'
那么增加-lz參數(shù)
相關(guān)文章
http://forums.devshed.com/t2352/s.html?highlight=perl+mysql+connection(DBI.pm)
連接數(shù)據(jù)庫(kù)test 用戶名root密碼abc
在里面有一個(gè)username的表，describe username結(jié)果如下
mysql> describe username;
+----------+-------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+----------+-------------+------+-----+---------+-------+
| id | int(10) | YES | | NULL | |
| username | varchar(32) | | PRI | | |
+----------+-------------+------+-----+---------+-------+
mysql> select * from username;
+------+----------+
| id | username |
+------+----------+
| 1 | sfs |
+------+----------+
1 row in set (0.00 sec)
本文目的查找執(zhí)行select id from username這個(gè)語(yǔ)句并打印結(jié)果
代碼:
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
MYSQL mysql;
main()
{
   char host[32]="localhost";
   char user[32]="root";
   char passwd[32]="abc";
   char dbname[32]="test";   
   
   if( mysql_init(&mysql) == NULL )
   {
      syslog(LOG_USER|LOG_INFO,"inital mysql handle errorn");
      return 1;
   }
   if (mysql_real_connect(&mysql,host,user,passwd,dbname,0,NULL,0) == NULL)
   {
      syslog(LOG_USER|LOG_INFO, "Failed to connect to database: Error: %sn",mysql_error(&mysql));
      return 1;
   }
   else syslog(LOG_USER|LOG_INFO, "connect to database: n");
   find_ps();   
   db_close();
   return 0;
}
int db_close()
{
        mysql_close(&mysql);
         return 0;
}
int  find_ps ()
{
   MYSQL_ROW m_row;
   MYSQL_RES *m_res;
   char sql[1024],username[32];
   int res=1;
   int *id;
   sprintf(sql,"select id from username");
   if(mysql_query(&mysql,sql) != 0)
   {
      syslog(LOG_USER|LOG_INFO, "select ps_info Error: %sn",mysql_error(&mysql));
      return res;
   }
   m_res = mysql_store_result(&mysql);
   if(m_res==NULL)
   {
      syslog(LOG_USER|LOG_INFO, "select username Error: %sn",mysql_error(&mysql));
      res = 3;
      return res;
   }
   if(m_row = mysql_fetch_row(m_res))
   {
      printf("m_row=%dn",atoi(m_row[0]));
      res = 0;      
   }
   mysql_free_result(m_res);
   return res;
}
編譯命令
gcc -g connect_db.c -L/usr/lib/mysql -lmysqlclient -lz
注意：
如果/tmp/ccTGmMS21.o: In function `main':
/tmp/ccTGmMS21.o(.text+0x11): undefined reference to `mysql_init'
那么參數(shù)增加-L/usr/lib/mysql -lmysqlclient
如果
usr/lib/mysql/libmysqlclient.a(my_compress.o): In function `my_uncompress':
my_compress.o(.text+0xaa): undefined reference to `uncompress'
那么增加-lz參數(shù)
相關(guān)文章
http://forums.devshed.com/t2352/s.html?highlight=perl+mysql+connection(DBI.pm)


本文來(lái)自ChinaUnix博客，如果查看原文請(qǐng)點(diǎn)：http://blog.chinaunix.net/u/476/showart_1898.html