我需要從ms sql表中放入並檢索大的二進制數據。如何使用WinApi從MS SQL表檢索大型二進制數據?
把數據我用ifstream和SQLPutData。這裏是我的代碼把數據(沒有錯誤檢查和分配一些手柄):
char file[MAX_PATH] = "";
strcpy(file, argv[2]);
ifstream f(file, ios::binary | ios::ate);
size_t sz = f.tellg();
f.seekg(0, ios::beg);
char *buf = new char[sz];
char *ptr = buf;
f.read(ptr, sz);
f.close();
SQLLEN lbytes, cbBinarySize;
PTR pParamID;
lbytes = (SDWORD) sz;
cbBinarySize = SQL_LEN_DATA_AT_EXEC(lbytes);
char SQL[512] = "INSERT INTO bindata (filename, binData) VALUES ('";
strcat(SQL, file);
strcat(SQL, "', ?)");
ret = SQLPrepare(stmt, (SQLCHAR *) SQL, SQL_NTS);
SQLSMALLINT dataType, decDigits, nullable;
SQLUINTEGER paramsize;
ret = SQLDescribeParam(stmt, 1, &dataType, ¶msize, &decDigits, &nullable);
ret = SQLBindParameter(stmt, 1, SQL_PARAM_INPUT, SQL_C_BINARY, dataType, paramsize, 0, (VOID *)1, 0, &cbBinarySize);
ret = SQLExecDirect(stmt, (SQLCHAR *) SQL, SQL_NTS);
if (ret != SQL_NEED_DATA && ret != SQL_SUCCESS && ret != SQL_SUCCESS_WITH_INFO) return ret;
ret = SQLParamData(stmt, &pParamID);
if (ret == SQL_NEED_DATA) {
while (lbytes > 5000) {
ret = SQLPutData(stmt, (SQLCHAR *)ptr, 5000);
lbytes -= 5000;
ptr += 5000;
}
ret = SQLPutData(stmt, ptr, lbytes);
ret = SQLParamData(stmt, &pParamID);
if (ret != SQL_SUCCESS) return ret;
}
SQLFreeHandle(SQL_HANDLE_STMT, stmt);
delete[] ptr;
delete[] buf;
這工作對我很好,我在我的VARBINARY(MAX)表中的字段的二進制數據。現在我想從那裏獲取這些數據。這是我試圖做的(我檢查了MSDN文章https://msdn.microsoft.com/en-us/library/ms811006.aspx):
unsigned char* data = new unsigned char[2500000];
SQLINTEGER cbFdata = SQL_NTS;
SQLAllocHandle(SQL_HANDLE_STMT, dbc, &stmt);
ret = SQLExecDirect(stmt, (SQLCHAR *) "SELECT binData FROM bindata WHERE filename='AgentCPP.exe'", SQL_NTS);
if (ret != SQL_SUCCESS && ret != SQL_SUCCESS_WITH_INFO) return ret;
ret = SQLFetch(stmt);
do {
ret = SQLGetData(stmt, 1, SQL_C_BINARY, data, 5000, &cbFdata);
} while (ret != SQL_NO_DATA_FOUND);
SQLFreeHandle(SQL_HANDLE_STMT, stmt);
但
而不是包含我的數據的數組,我得到一些垃圾,這可能只是我的數據的一部分。我究竟做錯了什麼? 如果我使用的是.Net,我可能會使用某種byte []數組,或者某種東西,但是在這裏我不能。你能幫我麼?UPD。只是試圖用C#來做,而我花了大約3分鐘和十幾行代碼。只是爲了顯示什麼結果,我試着讓 - 此代碼創建一個從二進制數據,這是從這個問題放進數據庫通過我的代碼第一塊完全正常的工作exe文件:
OdbcCommand com = new OdbcCommand(@"SELECT binData FROM bindata WHERE filename='AgentCPP.exe'", con);
com.Connection = con;
OdbcDataReader reader = com.ExecuteReader();
if (reader.Read())
binData = (byte[]) reader.GetValue(0);
reader.Dispose();
com.Dispose();
con.Close();
FileStream fs = new FileStream(@"agent.exe", FileMode.Create, FileAccess.Write);
fs.Write(binData, 0, binData.Length);
fs.Close();
哪有我使用c winapi實現相同?