ODBC Api, retrieve result SQLExecDirect

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Hi, i'm new in C++ and using the ODBC Api from Microsoft.
My question is how i retrieve the result of:

SQLExecDirect(hstmt, "Select Count(*) From Table", SQL_NTS);

It is a little confuse to me the use of the ODBC Api.

Thanks

Posted 20-Oct-14 9:06am

Member 11086796

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[no name] 20-Oct-14 15:23pm

http://msdn.microsoft.com/en-us/library/ms713611(v=vs.85).aspx

Member 11086796 20-Oct-14 15:37pm

Thanks for answer, I have already read the msdn, but I didn't understood it, so if you could post here an example code, i would be very grateful.

[no name] 20-Oct-14 15:46pm

And the problem with the sample code provided by the documentation would be...?

PIEBALDconsult 20-Oct-14 16:56pm

I think you now need SQLFetch, but it's been a few months since I was looking at the ODBC API.

PIEBALDconsult 20-Oct-14 23:37pm

When I was dabbling in ODBC a few months back it was with the following book:
http://www.amazon.com/ODBC-Developers-Guide-Roger-Sanders/dp/0070580871
which I had bought back in 1999. The information is still relevent.

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Vaclav Naydenov · Answer 1 · 2014-10-29T01:55:00

ODBC is a kind of API that is more easily understood by example.

C++

#include <stdio.h>
#include <sql.h>
#include <sqlext.h>
int main() {
    SQLHENV henv;  SQLHDBC hdbc;  SQLHSTMT hstmt;  SQLRETURN rc;
    /* allocate handles and connect */
    SQLAllocHandle(SQL_HANDLE_ENV, SQL_NULL_HANDLE, &henv);
    SQLSetEnvAttr(henv, SQL_ATTR_ODBC_VERSION, (void *)SQL_OV_ODBC3, 0);
    SQLAllocHandle(SQL_HANDLE_DBC, henv, &hdbc);
    rc = SQLConnect(hdbc, "dsn", SQL_NTS, "user", SQL_NTS, "pwd", SQL_NTS);
    if (!SQL_SUCCEEDED(rc)) { /* couldn't connect, process error, free resources */ }
    /* create a cursor and execute a statement */
    SQLAllocHandle(SQL_HANDLE_STMT, hdbc, &hstmt);
    rc = SQLExecDirect(hstmt, "Select Count(*) From Table", SQL_NTS);
    if (!SQL_SUCCEEDED(rc)) { /* couldn't exec sql, process error, free resources */ }
    /* fetch the result: here we expect single row with single column */
    rc = SQLFetch(hstmt);
    if (!SQL_SUCCEEDED(rc)) { /* couldn't fetch row, process error, free resources */ }
    /* extract data from the fetched row */
    SQLINTEGER indicator;  long count;
    rc = SQLGetData(hstmt, 1, SQL_C_LONG, &count, sizeof(count), &indicator);
    if (!SQL_SUCCEEDED(rc)) { /* couldn't convert to int, process error, free resources */ }
    if (indicator == SQL_NULL_DATA) { /* unexpected NULL, process error, free resources */ }
    printf("count = %ld\n", count);
    /* free resources: close the cursor */
    SQLFreeHandle(SQL_HANDLE_STMT, hstmt);
    /* disconnect from db */
    SQLFreeHandle(SQL_HANDLE_DBC, hdbc);
    SQLFreeHandle(SQL_HANDLE_ENV, henv);
    return 0;
}

Here is a compressed tutorial from EasySoft.
http://www.easysoft.com/developer/languages/c/odbc_tutorial.html[^]