今天给新来的同事做mysql培训，用到的一个例子：

连接数据库test 用户名root密码abc

在里面有一个username的表，describe username结果如下

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)

[b:f09d522785]本文目的查找执行select id from username这个语句并打印结果[/b:f09d522785]

[code:1:f09d522785]

#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 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; } [/code:1:f09d522785] 编译命令 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' 那么参数增加-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参数