如何用mysql 的c api 对jpg文件的读写？

[园区宅男]

数据表字段类型BLOB

读写数据的语句如何写？
请专家们指点。最好有例子，谢谢！

[gxg353]

一般的图片 数据库只是存取他的连接地址 图片还是放到硬盘上好

[tommy9802]

读写数据库的方法与字段类型没有太大关系吧，正常读写就行，你遇到问题或错误了吗？

[phpboy]

网上找了半天找了个例子 ..

http://www.anyexample.com/programming/php/php_mysql_example__image_gallery_(blob_storage).xml

[园区宅男]

void CBlobDlg::OnButton1() 
{
	// TODO: Add your control notification handler code here
	CFileDialogEx dlg(TRUE,_T(""),_T(""),OFN_HIDEREADONLY|OFN_OVERWRITEPROMPT,_T("照片文件(*.jpg)|*.jpg|"));
	if(IDOK==dlg.DoModal()){
		m_detail_picpath=dlg.GetPathName();
		UpdateData(FALSE);
	}
}

void CBlobDlg::OnButton2() 
{
	UpdateData(TRUE);
	// TODO: Add your control notification handler code here
	char   *opt_host_name   =   "vmxpcn";   
	char   *opt_user_name   =   "root";   
	char   *opt_password   =   "admin888";   
	unsigned   int   opt_port_num   =   3306;   
	char   *opt_socket_name   =   NULL;   
	char   *opt_db_name   =   "wipdebug";   
	unsigned   int   opt_flags   =   0;   
	MYSQL   *conn;   
    
	FILE   *f;   
    
	conn   =   mysql_init   (NULL);   
    
	mysql_real_connect   (conn,   opt_host_name,   opt_user_name,   opt_password,
		opt_db_name,   opt_port_num,   opt_socket_name,   opt_flags);
    
	if   ((f   =   fopen   (m_detail_picpath,   "rb"))   ==   NULL)
	{
		printf("file   open   eror!");
		return;
	}
	load_image   (conn,   f);
	fclose(f);   
    
	mysql_close   (conn);   

}

void CBlobDlg::load_image(MYSQL *conn, FILE *f)
{
	char query[1024*200],   buf[1024*100],   *p;
	unsigned long from_len;
    
	sprintf(query,"insert   into     repair_process   (RPIssuePic)   values   (   \'"   );
	p   =   query   +   strlen   (query);
	while   ((from_len   =   fread   (buf,   1,   sizeof   (buf),   f))   >   0)
	{
		if   (p   +   (2*from_len)   +   3   >   query   +   sizeof   (query))
		{
			printf("image   too   big");
			return;
		}
		p   +=   mysql_real_escape_string   (conn,   p,   buf,   from_len);
	}
	*p++   =   '\'';
	*p++   =   ')';
	strcpy(p,"   where   RPId=1");
    
//	mysql_query(conn,"set character set gbk");
//	TRACE(((char*)mysql_error(conn)));
	mysql_real_query   (conn,   query,   (unsigned   long)   (p-   query));

	TRACE(((char*)mysql_error(conn)));
}

插入示例图片：Blue hills.jpg没问题
插入示例图片：Sunset.jpg提示：Data too long for column 'RPIssuePic' at row 1

[园区宅男]

原因找到了，字段类型用"LONGBLOB"，没问题了。

[ljf_ljf]

[Quote=引用 2 楼 gxg353 的回复:]
一般的图片 数据库只是存取他的连接地址 图片还是放到硬盘上好
[/Quote]

完全赞同。

[ACMAIN_CHM]

如何用mysql提供的C API实现文件的存取?
http://topic.csdn.net/t/20030612/15/1907712.html#

MySQL C API 存取 blob这种例子应该很多了。 通过C读你的 图片二进制文件然后update到mysql

[园区宅男]

服务器只有mysql服务,没有http或ftp服务.

[ACMAIN_CHM]

没有HTTP，则只能用你的方法了，把图片文件写入到数据库。只是大部分场合不推荐这样做。

[园区宅男]

int CmysqlDatabase::UpdateBlob(Data_Param *para, FILE *f)
{
	char query[1024*800],buf[1024*100],*p=NULL,cwhere[256];
	unsigned long blob_len;
	mysql_query(&mysql,"set names 'utf8'");		//这一行很重要，否则可能会上传失败
	sprintf(query,"update %s set %s = \'",para->tab_name, para->set_exp);
	p = query + strlen (query);
	unsigned int bufsize = sizeof(buf);
	while((blob_len = fread (buf, 1, bufsize, f)) > 0)
	{
		if(p + (2*blob_len) + 3 > query + sizeof (query))
		{
			TRACE("image too big\n");
			return false;
		}
		p += mysql_real_escape_string(&mysql, p, buf, blob_len);
	}
	*p++ = '\'';
	sprintf(cwhere," where %s",para->where_def);
	int wherelen = strlen(cwhere);
	memcpy(p,cwhere,wherelen);
	p += wherelen;

	unsigned long lsize = (unsigned long)(p-query);
	if(mysql_real_query(&mysql, query, lsize))
	{
		TRACE(((char*)mysql_error(&mysql)));
		return false;
	}
	TRACE(((char*)mysql_error(&mysql)));
	return true;
}

//下面是调用
FILE *f;
if((f = fopen(m_issue_picpath, "rb")) == NULL)
{
	TRACE("file open eror!\n");
	m_issue_picpath = "照片文件打开失败！";
	UpdateData(FALSE);
	return;
}
theApp.mData.tab_name = "repair_process";
strwhere.Format("RPId = \'%d\'",iInsertId);
theApp.mData.where_def = (LPSTR)(LPCTSTR)strwhere;
strExp.Format("RPIssuePic");
theApp.mData.set_exp = (LPSTR)(LPCTSTR)strExp;

if(theApp.mwipd.UpdateBlob(&theApp.mData,f))
{
	TRACE("更新照片成功！\n");
}
else
	m_issue_picpath = "更新照片失败！";
fclose(f);