c連接mysql數據庫實例

連接數據庫test 用戶名root密碼abc

在里面有一個username的表，describe username結果如下

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)

本文目的查找執行select id from username這個語句并打印結果 CODE:＃i nclude ;

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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 error\n");

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: %s\n",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: %s\n",mysql_error(&mysql));

return res;

}

m_res = mysql_store_result(&mysql);

if(m_res==NULL)

{

syslog(LOG_USER|LOG_INFO, "select username Error: %s\n",mysql_error(&mysql));

res = 3;

return res;

}

if(m_row = mysql_fetch_row(m_res))

{

printf("m_row=%d\n",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

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