c 连接mysql

yymmlove 2008-05-27 02:46:43
请问各位高手,LINUX下如何用C语言连接MY SQL,希望给出具体例子和讲解.
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yymmlove 2008-06-18
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大哥，小弟是初学者，能不能解释一下获加一点注释，谢谢了
ngwsx 2008-06-08
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static ngx_int_t

ngx_dbd_mysql_close(ngx_dbd_t *dbd)

{

    if (dbd->res) {

		ngx_dbd_mysql_free_result(dbd->res);

    }



    if (dbd->tran) {

	    ngx_dbd_mysql_end_tran(dbd->tran);

    }



    if (dbd->mysql) {

	    ngx_log_debug1(NGX_LOG_DEBUG_MYSQL, dbd->log, 0,

			           "mysql_close(%p)", dbd->mysql);



	    mysql_close(dbd->mysql);



		dbd->mysql = NULL;

    }



    return NGX_OK;

}





static void *

ngx_dbd_mysql_native_handle(ngx_dbd_t *dbd)

{

    return dbd->mysql;

}





static ngx_int_t

ngx_dbd_mysql_check_conn(ngx_dbd_t *dbd)

{

    if (mysql_ping(dbd->mysql) != 0) {

		ngx_log_error(NGX_LOG_ALERT, dbd->log, 0,

			          "mysql_ping(%p) failed (%ud: %s)",

			          dbd->mysql,

			          mysql_errno(dbd->mysql), mysql_error(dbd->mysql));

		return NGX_ERROR;

    }



	ngx_log_debug1(NGX_LOG_DEBUG_MYSQL, dbd->log, 0,

		           "mysql_ping(%p)", dbd->mysql);



	return NGX_OK;

}





static ngx_int_t

ngx_dbd_mysql_select_db(ngx_dbd_t *dbd, u_char *dbname)

{

    if (mysql_select_db(dbd->mysql, (const char *) dbname) != 0) {

		ngx_log_error(NGX_LOG_ALERT, dbd->log, 0,

			          "mysql_select_db(%p, \"%s\") failed (%ud: %s)",

			          dbd->mysql, dbname,

			          mysql_errno(dbd->mysql), mysql_error(dbd->mysql));

		return NGX_ERROR;

    }



	ngx_log_debug2(NGX_LOG_DEBUG_MYSQL, dbd->log, 0,

		           "mysql_select_db(%p, \"%s\")", dbd->mysql, dbname);



	return NGX_OK;

}





static ngx_dbd_tran_t *

ngx_dbd_mysql_start_tran(ngx_dbd_t *dbd)

{

	ngx_dbd_tran_t  *tran;



	tran = dbd->tran;

    if (tran && tran->dbd) {

		return tran;

    }



	if (dbd->res) {

		ngx_dbd_mysql_free_result(dbd->res);

	}



	/* disable auto-commit */



	if (mysql_autocommit(dbd->mysql, 0) != 0) {

		ngx_log_error(NGX_LOG_ALERT, dbd->log, 0,

			          "mysql_autocommit(%p, 0) failed (%ud: %s)",

			          dbd->mysql,

			          mysql_errno(dbd->mysql), mysql_error(dbd->mysql));

		return NULL;

	}



    ngx_log_debug1(NGX_LOG_DEBUG_MYSQL, dbd->log, 0,

		           "mysql_autocommit(%p, 0)", dbd->mysql);



    if (tran == NULL) {

        tran = ngx_palloc(dbd->pool, sizeof(ngx_dbd_tran_t));

		if (tran == NULL) {

			return NULL;

		}



		dbd->tran = tran;

    }



	tran->dbd = dbd;

	tran->mode = NGX_DBD_TRANS_MODE_COMMIT;



	return tran;

}





static ngx_int_t

ngx_dbd_mysql_end_tran(ngx_dbd_tran_t *tran)

{

    int         rc;

    u_char     *name;

	ngx_dbd_t  *dbd;



	dbd = tran->dbd;

	if (dbd == NULL) {

		return NGX_OK;

	}



	if (dbd->res) {

		ngx_dbd_mysql_free_result(dbd->res);

	}



	/* commit or rollback transaction */



	if (NGX_DBD_TRANS_DO_COMMIT(tran)) {

		name = (u_char *) "mysql_commit";



		rc = mysql_commit(dbd->mysql);



	} else {

	    name = (u_char *) "mysql_rollback";



	    rc = mysql_rollback(dbd->mysql);

	}



	if (rc != 0) {

		ngx_log_error(NGX_LOG_ALERT, dbd->log, 0, "%s(%p) failed (%ud: %s)",

			          name, dbd->mysql,

			          mysql_errno(dbd->mysql), mysql_error(dbd->mysql));

		return NGX_ERROR;

	}



    ngx_log_debug2(NGX_LOG_DEBUG_MYSQL, dbd->log, 0,

		           "%s(%p)", name, dbd->mysql);



    /* enable auto-commit */



	if (mysql_autocommit(dbd->mysql, 1) != 0) {

		ngx_log_error(NGX_LOG_ALERT, dbd->log, 0,

		              "mysql_autocommit(%p, 1) failed (%ud: %s)",

		              dbd->mysql, mysql_errno(dbd->mysql),

                      mysql_error(dbd->mysql));

		return NGX_ERROR;

	}



	ngx_log_debug1(NGX_LOG_DEBUG_MYSQL, dbd->log, 0,

		           "mysql_autocommit(%p, 1)", dbd->mysql);



    tran->dbd = NULL;



    return NGX_OK;

}





static ngx_uint_t

ngx_dbd_mysql_get_tran_mode(ngx_dbd_tran_t *tran)

{

    if (tran == NULL) {

        return NGX_DBD_TRANS_MODE_COMMIT;

    }



    return tran->mode;

}
ngwsx 2008-06-08
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static ngx_dbd_t *

ngx_dbd_mysql_open(ngx_pool_t *pool, ngx_str_t *conn_str, ngx_log_t *log)

{

    MYSQL            *mysql;

	u_char           *host, *user, *pass, *dbname, *sock, *group;

	ngx_dbd_t        *dbd;

	ngx_uint_t        n, i, port, flags, fldsz;

	ngx_array_t      *params;

	ngx_keyval_t     *kv;

#if MYSQL_VERSION_ID >= 50013

    my_bool 		  reconnect;

#endif

#if (NGX_DEBUG)

    MY_CHARSET_INFO   csi;

#endif



    /* parse connection string */



    params = ngx_p2sp_parse_str(conn_str, NGX_P2SP_PARSE_COPY_STR, pool);

    if (params == NULL) {

		ngx_log_error(NGX_LOG_ALERT, log, 0,

		              "invalid connection string: \"%V\"", conn_str);

	    return NULL;

	}



	host = NULL;

	user = NULL;

	pass = NULL;

	dbname = NULL;

	sock = NULL;

	group = NULL;

	port = 3306;

	flags = CLIENT_MULTI_STATEMENTS;

	fldsz = NGX_DBD_MYSQL_FIELDSIZE;



    kv = params->elts;

	n = params->nelts;



	for (i = 0; i < n; i++) {



		if (ngx_strncmp(kv[i].key.data, "host", kv[0].key.len) == 0) {

			host = kv[i].value.data;



		} else if (ngx_strncmp(kv[i].key.data, "user", kv[i].key.len) == 0) {

			user = kv[i].value.data;



		} else if (ngx_strncmp(kv[i].key.data, "passwd", kv[i].key.len) == 0) {

			pass = kv[i].value.data;



		} else if (ngx_strncmp(kv[i].key.data, "dbname", kv[i].key.len) == 0) {

			dbname = kv[i].value.data;



		} else if (ngx_strncmp(kv[i].key.data, "sock", kv[i].key.len) == 0) {

			sock = kv[i].value.data;



		} else if (ngx_strncmp(kv[i].key.data, "group", kv[i].key.len) == 0) {

			group = kv[i].value.data;



		} else if (ngx_strncmp(kv[i].key.data, "port", kv[i].key.len) == 0) {

			port = ngx_atoi(kv[i].value.data, kv[i].value.len);



		} else if (ngx_strncmp(kv[i].key.data, "flags", kv[i].key.len) == 0) {

			if (ngx_strstrn(kv[i].value.data, "CLIENT_FOUND_ROWS",

				            kv[i].value.len))

		    {

		        flags |= CLIENT_FOUND_ROWS;

		    }



		} else if (ngx_strncmp(kv[i].key.data, "fldsz", kv[i].key.len) == 0) {

			fldsz = ngx_atoi(kv[i].value.data, kv[i].value.len);



		} else {

		    /* TODO */

		}

	}



	mysql = mysql_init(NULL);

	if (mysql == NULL) {

		return NULL;

	}



	ngx_log_debug1(NGX_LOG_DEBUG_MYSQL, log, 0, "mysql_init: %p", mysql);



    if (group) {

        if (mysql_options(mysql, MYSQL_READ_DEFAULT_GROUP, group) != 0) {

	        ngx_log_error(NGX_LOG_ALERT, log, 0,

				          "mysql_options(MYSQL_READ_DEFAULT_GROUP, "

				          "\"%s\") failed", group);

        }

    }



#if MYSQL_VERSION_ID >= 50013



    reconnect = 1;



    if (mysql_options(mysql, MYSQL_OPT_RECONNECT, &reconnect) != 0) {

		ngx_log_error(NGX_LOG_ALERT, log, 0,

			          "mysql_options(MYSQL_OPT_RECONNECT, %ui) failed",

			          reconnect);

    }



#endif



	if (mysql_real_connect(mysql, (const char *) host, user, pass, dbname,

		                   (unsigned int) port, sock, (unsigned int) flags)

        == NULL)

    {

		ngx_log_error(NGX_LOG_ALERT, log, 0,

			          "mysql_real_connect(\"%V\") failed (%ud: %s)",

			          conn_str, mysql_errno(mysql), mysql_error(mysql));

		mysql_close(mysql);

		return NULL;

	}



	ngx_log_debug2(NGX_LOG_DEBUG_MYSQL, log, 0,

			       "mysql_real_connect(\"%V\") %p", conn_str, mysql);





    /* TODO: 设置连接使用的字符集，外部可通过在连接字符串中指定 */



    ngx_log_debug1(NGX_LOG_DEBUG_MYSQL, log, 0,

		           "mysql_character_set_name: %s",

		           mysql_character_set_name(mysql));



#if 0

	if (mysql_set_character_set(mysql, "gb2312") != 0) {

		ngx_log_error(NGX_LOG_ALERT, log, 0,

			          "mysql_set_character_set(%p, \"gb2312\") "

			          "failed (%ud: %s)",

			          mysql, mysql_errno(mysql), mysql_error(mysql));



	} else {

		ngx_log_debug1(NGX_LOG_DEBUG_MYSQL, log, 0,

			           "mysql_set_character_set(%p, \"gb2312\")", mysql);

	}

#endif



#if (NGX_DEBUG)



	mysql_get_character_set_info(mysql, &csi);



    ngx_log_debug1(NGX_LOG_DEBUG_MYSQL, log, 0,

		           "character set number: %ud", csi.number);

	ngx_log_debug1(NGX_LOG_DEBUG_MYSQL, log, 0,

		           "character set state: %ud", csi.state);

    ngx_log_debug1(NGX_LOG_DEBUG_MYSQL, log, 0,

		           "character set name: %s", csi.name);

    ngx_log_debug1(NGX_LOG_DEBUG_MYSQL, log, 0,

		           "collation name: %s", csi.csname);

    /*ngx_log_debug1(NGX_LOG_DEBUG_MYSQL, log, 0,

		           "comment: %s", csi.comment ? csi.comment : "NULL");*/

    ngx_log_debug1(NGX_LOG_DEBUG_MYSQL, log, 0,

		           "character set directory: %s", csi.dir ? csi.dir : "NULL");

    ngx_log_debug1(NGX_LOG_DEBUG_MYSQL, log, 0,

		           "multibyte strings min length: %ud", csi.mbminlen);

    ngx_log_debug1(NGX_LOG_DEBUG_MYSQL, log, 0,

		           "multibyte strings max length: %ud", csi.mbmaxlen);



#endif



    ngx_log_debug1(NGX_LOG_DEBUG_MYSQL, log, 0,

                   "mysql_get_host_info: %s", mysql_get_host_info(mysql));



    ngx_log_debug1(NGX_LOG_DEBUG_MYSQL, log, 0,

                   "mysql_get_proto_info: %ud", mysql_get_proto_info(mysql));



	ngx_log_debug1(NGX_LOG_DEBUG_MYSQL, log, 0,

                   "mysql_get_server_info: %s", mysql_get_server_info(mysql));



	ngx_log_debug1(NGX_LOG_DEBUG_MYSQL, log, 0,

                   "mysql_get_server_version: %ul",

                   mysql_get_server_version(mysql));



	ngx_log_debug1(NGX_LOG_DEBUG_MYSQL, log, 0,

		           "mysql_stat: %s", mysql_stat(mysql));





	dbd = ngx_palloc(pool, sizeof(ngx_dbd_t));

	if (dbd == NULL) {

		mysql_close(mysql);

		return NULL;

	}



    dbd->mysql = mysql;

	dbd->log = log;

    dbd->pool = pool;

	dbd->fldsz = fldsz;

	dbd->res = NULL;

	dbd->tran = NULL;

	dbd->escaped.data = NULL;

	dbd->escaped.len = 0;



	return dbd;

}
ngwsx 2008-06-08
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/*

 * Copyright (C) ngwsx

 */





#include <ngx_config.h>

#include <ngx_core.h>

#include <ngx_dbd.h>

#include <ngx_p2sp.h>





#if (NGX_DBD_MYSQL)



#include <mysql/mysql.h>





static ngx_int_t ngx_dbd_mysql_init(ngx_cycle_t *cycle);

static void ngx_dbd_mysql_done(ngx_cycle_t *cycle);



static ngx_dbd_t *ngx_dbd_mysql_open(ngx_pool_t *pool, ngx_str_t *conn_str,

    ngx_log_t *log);

static ngx_int_t ngx_dbd_mysql_close(ngx_dbd_t *dbd);



static void *ngx_dbd_mysql_native_handle(ngx_dbd_t *dbd);

static ngx_int_t ngx_dbd_mysql_check_conn(ngx_dbd_t *dbd);

static ngx_int_t ngx_dbd_mysql_select_db(ngx_dbd_t *dbd, u_char *dbname);



static ngx_dbd_tran_t *ngx_dbd_mysql_start_tran(ngx_dbd_t *dbd);

static ngx_int_t ngx_dbd_mysql_end_tran(ngx_dbd_tran_t *tran);

static ngx_uint_t ngx_dbd_mysql_get_tran_mode(ngx_dbd_tran_t *tran);

static ngx_uint_t ngx_dbd_mysql_set_tran_mode(ngx_dbd_tran_t *tran,

	ngx_uint_t mode);



static ngx_int_t ngx_dbd_mysql_exec(ngx_dbd_t *dbd, u_char *sql,

	int *affected);

static ngx_dbd_res_t *ngx_dbd_mysql_query(ngx_dbd_t *dbd, u_char *sql,

	ngx_uint_t random);



static int ngx_dbd_mysql_num_fields(ngx_dbd_res_t *res);

static int ngx_dbd_mysql_num_rows(ngx_dbd_res_t *res);



static const ngx_str_t *ngx_dbd_mysql_field_name(ngx_dbd_res_t *res, int col);

static ngx_dbd_row_t *ngx_dbd_mysql_fetch_row(ngx_dbd_res_t *res, int row);

static const ngx_str_t *ngx_dbd_mysql_fetch_field(ngx_dbd_row_t *row, int col);

static ngx_int_t ngx_dbd_mysql_datum_get(ngx_dbd_row_t *row, int col,

	ngx_dbd_type_e type, void *data);



static const u_char *ngx_dbd_mysql_escape(ngx_dbd_t *dbd, const u_char *str);



static int ngx_dbd_mysql_errno(ngx_dbd_t *dbd);

static const u_char *ngx_dbd_mysql_strerror(ngx_dbd_t *dbd);





static ngx_str_t         ngx_dbd_mysql_name = ngx_string("mysql");





static ngx_dbd_module_t  ngx_dbd_mysql_module_ctx = {

    NULL,

	NULL,



    { &ngx_dbd_mysql_name,

      ngx_dbd_mysql_init,

      ngx_dbd_mysql_done,

      ngx_dbd_mysql_open,

      ngx_dbd_mysql_close,

      ngx_dbd_mysql_native_handle,

      ngx_dbd_mysql_check_conn,

      ngx_dbd_mysql_select_db,

      ngx_dbd_mysql_start_tran,

      ngx_dbd_mysql_end_tran,

      ngx_dbd_mysql_get_tran_mode,

      ngx_dbd_mysql_set_tran_mode,

      ngx_dbd_mysql_exec,

      ngx_dbd_mysql_query,

      ngx_dbd_mysql_num_fields,

      ngx_dbd_mysql_num_rows,

      ngx_dbd_mysql_field_name,

      ngx_dbd_mysql_fetch_row,

      ngx_dbd_mysql_fetch_field,

      ngx_dbd_mysql_datum_get,

      ngx_dbd_mysql_escape,

      ngx_dbd_mysql_errno,

      ngx_dbd_mysql_strerror }

};





ngx_module_t  ngx_dbd_mysql_module = {

    NGX_MODULE_V1,

    &ngx_dbd_mysql_module_ctx,     /* module context */

    NULL,                          /* module directives */

    NGX_DBD_MODULE,                /* module type */

    NULL,                          /* init master */

    NULL,                          /* init module */

    NULL,                          /* init process */

    NULL,                          /* init thread */

    NULL,                          /* exit thread */

    NULL,                          /* exit process */

    NULL,                          /* exit master */

    NGX_MODULE_V1_PADDING

};





/* default maximum field size 1MB */



#define NGX_DBD_MYSQL_FIELDSIZE  1048575





struct ngx_dbd_s {

	MYSQL                *mysql;

	ngx_uint_t            fldsz;

	ngx_str_t             escaped;

	ngx_dbd_res_t        *res;

    ngx_dbd_tran_t       *tran;

	ngx_log_t            *log;

	ngx_pool_t           *pool;

};





struct ngx_dbd_tran_s {

	ngx_uint_t            mode;

    ngx_dbd_t            *dbd;

};





struct ngx_dbd_res_s {

	MYSQL_RES            *res;

	MYSQL_STMT           *stmt;

	ngx_uint_t            random;

	ngx_str_t             field_name;

	ngx_dbd_row_t        *row;

	ngx_dbd_t            *dbd;

};





struct ngx_dbd_row_s {

	MYSQL_ROW             row;

	ngx_uint_t           *lengths;

	ngx_str_t             field;

    ngx_dbd_res_t        *res;

};





static void

ngx_dbd_mysql_free_result(ngx_dbd_res_t *res)

{

    if (res->res == NULL) {

		return;

    }



	if (!res->random) {

		while (mysql_fetch_row(res->res)) {}

	}



	ngx_log_debug1(NGX_LOG_DEBUG_MYSQL, res->dbd->log, 0,

		           "mysql_free_result(%p)", res->res);



	mysql_free_result(res->res);



	res->res = NULL;

}





static ngx_int_t

ngx_dbd_mysql_init(ngx_cycle_t *cycle)

{

    if (mysql_library_init(0, NULL, NULL) != 0) {

		ngx_log_error(NGX_LOG_ALERT, cycle->log, 0,

			          "mysql_library_init() failed");

		return NGX_ERROR;

    }



    ngx_log_debug0(NGX_LOG_DEBUG_MYSQL, cycle->log, 0, "mysql_library_init()");



    ngx_log_debug1(NGX_LOG_DEBUG_MYSQL, cycle->log, 0,

                   "mysql_get_client_info: %s", mysql_get_client_info());



	ngx_log_debug1(NGX_LOG_DEBUG_MYSQL, cycle->log, 0,

		           "mysql_get_client_version: %ul", mysql_get_client_version());



	ngx_log_debug1(NGX_LOG_DEBUG_MYSQL, cycle->log, 0,

		           "mysql_thread_safe: %ud", mysql_thread_safe());



	return NGX_OK;

}





static void

ngx_dbd_mysql_done(ngx_cycle_t *cycle)

{

    mysql_thread_end();



	ngx_log_debug0(NGX_LOG_DEBUG_MYSQL, cycle->log, 0, "mysql_thread_end()");



    mysql_library_end();



    ngx_log_debug0(NGX_LOG_DEBUG_MYSQL, cycle->log, 0, "mysql_library_end()");

}
jose2gether4ever 2008-06-05
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楼上正解，我也用过。
noliper 2008-06-05
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楼上,楼上的楼上均为正解.如果还不能编译,将mysql.h的路径改成绝对路径.
jufeng2309 2008-05-27
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#include <mysql.h>
#include <stdio.h>
int main()
{
MYSQL mysql; // need a instance to init
MYSQL_RES *res;
MYSQL_ROW row;
char *query;
int t,r;
mysql_init(&mysql);
if(!mysql_real_connect(&mysql,"localhost", "username", "password", "test",0,NULL,0))
{
printf( "Error connecting to database: %s\n",mysql_error(&mysql));
}
else
printf("Connected...\n");

query = "select * from t1";

t = mysql_real_query(&mysql,query,(unsigned int) strlen(query));
if (t)
{
printf("Error making query: %s\n",
mysql_error(&mysql));
}
else printf("[%s] made...\n", query);
res = mysql_store_result(&mysql);
while(row = mysql_fetch_row(res))
{
for(t=0;t<mysql_num_fields(res);t++)
{
printf("%s ",row[t]);
}
printf("\n");
}

printf("mysql_free_result...\n");
mysql_free_result(res);

mysql_close(&mysql);

return 0;
}

test数据库和t1表均已建立.用如下命令编译:
gcc -o testsql testsql.c -I/usr/include/mysql -L/usr/lib/mysql -lmysqlclient
Godbach 2008-05-27
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首先要include MySQL的头文件，
然后知道MySQL头文件提供的API，即可在C中调用，
编译的时候记得链接MySQL的动态库文件
用C语言连接mysql
Windows下 用C语言连接mysql
c语言连接mysql数据库
在我们做C项目用到mysql数据库时需要进行和mysql进行连接，而连接mysql的步骤中几乎时固定的，因此可以写在文件中保存以备用。（文件中main函数中两个printf函数的输出为测试结果，调用连接函数前为NULL,调用连接函数后为一个地址，mysqlConnect函数中第一个参数为数据库所在ip,第二个和第三个参数是c编译所在环境的用户名和密码，第四个参数是要连接的数据库database名称）。
Mysql数据库基础入门视频教程
Mysql数据库基础入门视频课程：属于零基础Mysql数据库教程，从数据库的基本专业术语介绍到数据库软件的下载使用一步一步带你安装MySql。SQL阶段你将学会如果使用数据定义语言DDL,数据操作语言DML,数据查询语言DQL在学会各中查询语句之后,会带你学习数据的完整性, 掌握如果正确的向数据库中添加数据以上掌握技能之后,将会带你学习如何进行多表操作,关系的建立,各种连接查询等.常用函数,事务的学习,您将学到什么是事务的提交,回滚,并发操作及脏读,幻读.最后视图,存储过程,索引的学习,将会带你掌握更高级的数据库技术.
C语言连接mysql成功
Linux下编程 C语言连接mysql C连接mysql
C语言连接mysql
C语言连接mysql
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