Calling an MS SQL Stored Procedure in C++ - c++

Question

I'm writing an application that connects to a stored procedure on an MS SQL (2012) Server. The procedure is for inserting data to the database. I'm having real trouble understanding how to define the connection to the stored procedure, bind variables to the parameters and associating those parameters with the variables in the stored procedure. I've spent a few days wading through MSDN reading the APIs and trying to follow examples on here, but there seem to be so many ways of doing this that I can't see the 'wood for the trees'. I think I have the basic structure in place, but I'm falling down on the detail.
Below is the code I have so far. I've omitted the database connection code for simplicity. The function is part of a class 'rigDatabase' which has private members for the various SQL handles.
The main issue I'm having is with the calls to SQLSetDescField. Based on the documentation and examples provided by Microsoft, these calls should work, but instead return HY092 - "Invalid attribute/option identifier". This is what I need help with. Recently I tried logging the output from the ODBC Driver manager to see if that shed any light on the matter. The output to one of the calls to SQLSetDescField can be seen below the Stored Procedure definition.
NB: I haven't yet tried the simpler method of embedding the SQL in the C. I'm trying to interface with existing infrastructure (the Stored Proc).
SQLRETURN rigDatabase::send_SQL(const char* filename,
const char* extn,
const char* path,
DWORD& fSize,
const char* rigName,
FILETIME& created,
const char* notes) {
SQLHDESC hIpd = NULL;
SQLINTEGER PartIDInd = 0;
SQL_TIMESTAMP_STRUCT datetime2;
datetime2.year = fileDate.wYear;
datetime2.month = fileDate.wMonth;
datetime2.day = fileDate.wDay;
datetime2.hour = fileDate.wHour;
datetime2.minute = fileDate.wMinute;
datetime2.second = fileDate.wSecond;
datetime2.fraction = fileDate.wMilliseconds;
retcode = SQLPrepareA(sqlStmtHandle, (SQLCHAR*)"{call insertTestRigDataTest(?, ?, ?, ?, ?, ?, ?)}", SQL_NTS);
retcode = SQLBindParameter(sqlStmtHandle, 1, SQL_PARAM_INPUT, SQL_C_CHAR, SQL_CHAR, FILENAME_MAX, 0, (SQLPOINTER)filename, 0, NULL);
retcode = SQLBindParameter(sqlStmtHandle, 2, SQL_PARAM_INPUT, SQL_C_CHAR, SQL_CHAR, MAX_PATH, 0, (SQLPOINTER)path, 0, NULL);
retcode = SQLBindParameter(sqlStmtHandle, 3, SQL_PARAM_INPUT, SQL_C_CHAR, SQL_CHAR, BUF_SIZE, 0, (SQLPOINTER)rigName, 0, NULL);
retcode = SQLBindParameter(sqlStmtHandle, 4, SQL_PARAM_INPUT, SQL_C_ULONG, SQL_INTEGER, 0, 0, (SQLPOINTER)fSize, 0, &PartIDInd);
retcode = SQLBindParameter(sqlStmtHandle, 5, SQL_PARAM_INPUT, SQL_C_CHAR, SQL_CHAR, 4, 0, (SQLPOINTER)extn, 0, NULL);
retcode = SQLBindParameter(sqlStmtHandle, 6, SQL_PARAM_INPUT, SQL_C_TYPE_TIMESTAMP, SQL_TYPE_TIMESTAMP, sizeof(SQL_TIMESTAMP_STRUCT), 0, &datetime2, 0, NULL);
retcode = SQLBindParameter(sqlStmtHandle, 7, SQL_PARAM_INPUT, SQL_C_CHAR, SQL_CHAR, 4000, 0, (SQLPOINTER)notes, 0, NULL);
retcode = SQLGetStmtAttrA(sqlStmtHandle, SQL_ATTR_IMP_PARAM_DESC, &hIpd, 0, 0);
// All calls to SQLSetDescField below return -1
// SQLGetDiagRecA returns "Invalid attribute/option identifier"
retcode = SQLSetDescField(hIpd, 1, SQL_DESC_NAME, "#Filename", SQL_NTS);
retcode = SQLSetDescField(hIpd, 2, SQL_DESC_NAME, "#Path", SQL_NTS);
retcode = SQLSetDescField(hIpd, 3, SQL_DESC_NAME, "#Rigname", SQL_NTS);
retcode = SQLSetDescField(hIpd, 4, SQL_DESC_NAME, "#Size", SQL_NTS);
retcode = SQLSetDescField(hIpd, 5, SQL_DESC_NAME, "#Extn", SQL_NTS);
retcode = SQLSetDescField(hIpd, 6, SQL_DESC_NAME, "#Created", SQL_NTS);
retcode = SQLSetDescField(hIpd, 7, SQL_DESC_NAME, "#Notes", SQL_NTS);
retcode = SQLExecute(sqlStmtHandle);
return EXIT_FAILURE;
}
// Function to convert from FILETIME to int64
unsigned __int64 FILETIME_to_int64( const FILETIME& ac_FileTime ) {
ULARGE_INTEGER lv_Large;
lv_Large.LowPart = ac_FileTime.dwLowDateTime;
lv_Large.HighPart = ac_FileTime.dwHighDateTime;
return lv_Large.QuadPart;
}
MS SQL Stored Procedure
USE [TestRigDataTest]
GO
/****** Object: StoredProcedure [dbo].[insertTestRigDataTest] Script Date: 16/10/2018 10:14:34 ******/
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
ALTER PROCEDURE [dbo].[insertTestRigDataTest]
(
#fileName nvarchar(255),
#path nvarchar(255),
#rigName nvarchar(255),
#size [numeric](18, 0),
#extn nvarchar(255),
#created [datetime],
#notes nvarchar(4000) = NULL
)
AS
BEGIN
SET NOCOUNT ON;
declare #id int
declare #tmpNotes nvarchar(4000)
set #tmpNotes=''
select #id=id,#tmpNotes=notes from [TestRigDataTest].[dbo].[RigData]
where
[Filename]=#filename and
[Path]=#Path and
[Size]=#Size and
[Extension]=#Extn and
[created]=#created
if ##rowcount=0
begin
INSERT INTO [TestRigDataTest].[dbo].[RigData] (
[Filename], [Path], [Rigname] ,[UploadDate] ,[Size] ,[Extension] ,[created] ,[notes]
)
VALUES (
#fileName, #path, #rigName, getdate(), #size, #extn, #created, #notes
)
end
else
begin
if #notes != ''
begin
update [TestRigDataTest].[dbo].[RigData] set [notes]=#tmpNotes + CHAR(13)+CHAR(10) + #notes
where id=#id
end
end
END
ODBC Driver Manager Partial Trace Log:
NB: SQLSetDescField is #defined to SQLSetDescFieldW
AirCatFeeder 26f0-1e50 ENTER SQLSetDescFieldW
SQLHDESC 0x00000000004CB9E8
SQLSMALLINT 2
SQLSMALLINT 1011 <SQL_DESC_NAME>
SQLPOINTER 0x000000013FBA15EC [ -3] "??h\ 0"
SQLINTEGER -3
AirCatFeeder 26f0-1e50 ENTER SQLSetDescField
SQLHDESC 0x00000000004CB9E8
SQLSMALLINT 2
SQLSMALLINT 1011 <SQL_DESC_NAME>
SQLPOINTER 0x000000013FBA15EC [ -3] "#Path\ 0"
SQLINTEGER -3
AirCatFeeder 26f0-1e50 EXIT SQLSetDescField with return code -1 (SQL_ERROR)
SQLHDESC 0x00000000004CB9E8
SQLSMALLINT 2
SQLSMALLINT 1011 <SQL_DESC_NAME>
SQLPOINTER 0x000000013FBA15EC [ -3] "#Path\ 0"
SQLINTEGER -3
DIAG [HY092] [Microsoft][ODBC SQL Server Driver]Invalid attribute/option identifier (0)
AirCatFeeder 26f0-1e50 EXIT SQLSetDescFieldW with return code -1 (SQL_ERROR)
SQLHDESC 0x00000000004CB9E8
SQLSMALLINT 2
SQLSMALLINT 1011 <SQL_DESC_NAME>
SQLPOINTER 0x000000013FBA15EC [ -3] "??h\ 0"
SQLINTEGER -3
DIAG [HY092] [Microsoft][ODBC SQL Server Driver]Invalid attribute/option identifier (0)

Answer 1

The issue was the use of wide strings. SQLSetDescField #defines to SQLSetDescFieldW, but the string literal was not marked as being a wide string. I was missing the 'L' before the string definietion. A sample of the correct code is below.
retcode = SQLSetDescField(hIpd, 1, SQL_DESC_NAME, L"#filename", SQL_NTS);
Interesting to note that I tried using demo code from MSDN, which is based on wide strings, but their own code featured this error. Very frustrating when you're trying to learn, but perhaps they're being like the old meccano kits - putting in deliberate errors. I certainly won't be forgetting this lesson!