C++ MySQL存储二进制数据

0x01

首先MySQL支持二进制的类型有Blob:

MySQL的四种BLOB类型

类型 大小(单位：字节)

TinyBlob 最大 255

Blob 最大 65K

MediumBlob 最大 16M

LongBlob 最大 4G

0x02

插入二进制数据时需要利用mysql_real_escape_string函数对数据进行转换

0x03

读取二进制数据时需要利用mysql_fetch_length函数字段长度,该函数需要在mysql_fetch_row调用后才可以正常获取结果

0x04

写入例子：

int  CFinger_PrintDlg::Connect_Mysql(byte b_name[], byte* b_data,int len_of_data) {

const char user[] = "root";
const char pswd[] = "toor";
const char host[] = "127.0.0.1";
const char db[] = "Fingerprint";

int res;
int listrow = 0;
char sql_buf[100] = {};
unsigned int port = 3306;
bool return_result = false;
MYSQL myCont;
MYSQL_RES *result;
MYSQL_ROW sql_row;
HWND hWnd = GetSafeHwnd();
TCHAR sql_buf_t[100] = {};
//CListCtrl* list = (CListCtrl*)GetDlgItem(IDC_LIST3);
mysql_init(&myCont);

if (mysql_real_connect(&myCont, host, user, pswd, db, port, NULL, 0))
{
PostMessage(WM_MyMessage, (WPARAM)&L"连接数据库成功！！", (LPARAM)NULL);

}
mysql_query(&myCont, "SET NAMES GBK"); //设置编码格式
char buf[2000] = { NULL };

unsigned int escape_size = 2 * len_of_data + 2;
char* escape_object = (char *)malloc(escape_size);
escape_size = mysql_real_escape_string(&myCont, (char*)escape_object, (char *)b_data, len_of_data);

int sql_len = sprintf_s(buf, "insert into finger3(info) values('%s')", escape_object);
res = mysql_real_query(&myCont,buf, sql_len);

if (!res)
{

return_result = TRUE;
if (!res)
{

PostMessage(WM_MyMessage, (WPARAM)L"写入成功", NULL);

}
}
else
{
PostMessage(WM_MyMessage, (WPARAM)L"写入失败", NULL);
}

mysql_close(&myCont);

return return_result;
}

0x05

读取操作：

void* CFinger_PrintDlg::Read_Mysql()
{
if (!g_connect){
SendMessage(WM_MyMessage, (WPARAM)L"数据库未连接...", NULL);
return 0;
}

MYSQL_RES *res = NULL;
MYSQL_ROW row;
unsigned long *row_len;
char *object = NULL;
//const char *sql = "select info from final where id=";
char sql[100] = { NULL };
unsigned long objsize;
int ret;
for (int i = 1; i <= 10; i++){

sprintf_s(sql, "select info from final where id='%d'", i);

ret = mysql_real_query(&myCont, sql, strlen(sql));
if (ret){
PostMessage(WM_MyMessage, (WPARAM)L"读取失败1", NULL);
}

res = mysql_store_result(&myCont);
if (res == NULL){
PostMessage(WM_MyMessage, (WPARAM)L"读取失败2", NULL);
}

/* important */
row = mysql_fetch_row(res);
row_len = mysql_fetch_lengths(res);  /* get the object's length */
if (row_len == NULL){
PostMessage(WM_MyMessage, (WPARAM)L"读取失败3", NULL);
}

objsize = row_len[0];
object = (char*)malloc(objsize);
if (object == NULL){
PostMessage(WM_MyMessage, (WPARAM)L"读取失败4", NULL);
}

memcpy(object, row[0], objsize);

if (BIOKEY_DB_ADD(ZKFingerHandle, i, objsize, (byte*)object)){

PostMessage(WM_MyMessage, (WPARAM)L"读取成功", NULL);
}

}
g_connect = false;
;
//mysql_close(&myCont);
mysql_free_result(res);
return NULL;

}

0x06

更新操作：

int CFinger_PrintDlg::Updata_Mysql(byte b_name[], byte* b_data, int len_of_data){

if (!g_connect){
SendMessage(WM_MyMessage, (WPARAM)L"数据库未连接...", NULL);
return 0;
}
int res;
bool return_result = false;

mysql_query(&myCont, "SET NAMES GBK"); //设置编码格式
char buf[2000] = { NULL };

unsigned int escape_size = 2 * len_of_data + 2;
char* escape_object = (char *)malloc(escape_size);
escape_size = mysql_real_escape_string(&myCont, (char*)escape_object, (char *)b_data, len_of_data);
CString id_cs;
CString name_cs;
int id;
char name[20] = { NULL };
GetDlgItem(IDC_EDIT1)->GetWindowTextW(id_cs);
GetDlgItem(IDC_EDIT2)->GetWindowTextW(name_cs);
id = _wtoi(id_cs);
WideCharToMultiByte(CP_ACP, 0, name_cs, -1, name, name_cs.GetLength(), NULL, NULL);

//int sql_len = sprintf_s(buf, "insert into final(id,name,info) values('%d','%s','%s')", id, name, escape_object);
//UPDATE 表名称 SET 列名称 = 新值 WHERE 列名称 = 某值
int sql_len = sprintf_s(buf, "UPDATE final SET name='%s',info='%s' where id ='%d'", name, escape_object, id);
res = mysql_real_query(&myCont, buf, sql_len);

if (!res)
{

return_result = TRUE;
if (!res)
{

PostMessage(WM_MyMessage, (WPARAM)L"更新成功", NULL);

}
}
else
{
PostMessage(WM_MyMessage, (WPARAM)L"更新失败", NULL);
}

//mysql_close(&myCont);
g_connect = false;
return return_result;

}