After Connecting, you can allocate a statement handle and execute the statement.

SELECT Procedure

Use SQLExecDirect to execute the statement and SQLFetch to fetch the records. You can use SQLBindCol to bind variables to columns in the result set. The numbering of the result set columns starts at 1.

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); 
SQLDriverConnect(hdbc, 0, (SQLCHAR*)"Dsn=CData Box Source", SQL_NTS, 0, 0, 0, 0);
SQLAllocHandle(SQL_HANDLE_STMT, hdbc, &hstmt);
SQLExecDirect(hstmt, (SQLCHAR*)"SELECT Name FROM Files WHERE Id = '123'", SQL_NTS);  
SQLCHAR sName[20] = {0};
SQLLEN cbName = 0;
SQLBindCol(hstmt, 1, SQL_C_CHAR, sName, 20, &cbName);
SQLRETURN retcode = SQLFetch(hstmt);
if (retcode == SQL_SUCCESS || retcode == SQL_SUCCESS_WITH_INFO) {
 ...
}

Iterating over the Results

You can use SQLGetData to get values while iterating through a cursor. To iterate over the results, use SQLFetch to fetch rows and SQLGetData to retrieve the column values.

  SQLHENV henv;
  SQLHDBC hdbc;
  SQLHSTMT hstmt;
  char sId[255] = {0};
  SQLLEN cbId = 0;
  if (SQLAllocHandle(SQL_HANDLE_ENV, 0 ,&henv) == SQL_SUCCESS) {
    SQLSetEnvAttr(henv, SQL_ATTR_ODBC_VERSION, (void*)SQL_OV_ODBC3, 0); 
    if (SQLAllocHandle(SQL_HANDLE_DBC, henv ,&hdbc) == SQL_SUCCESS) {
      if (SQLConnect(hdbc, "CData Box Source", SQL_NTS, 0, 0, 0, 0) == SQL_SUCCESS) {
        if (SQLAllocHandle(SQL_HANDLE_STMT, hdbc ,&hstmt) == SQL_SUCCESS) {
          if (SQLExecDirect(hstmt, "SELECT Id FROM Files WHERE Id = '123'", SQL_NTS) == SQL_SUCCESS) {
            while(SQLFetch(hstmt) == SQL_SUCCESS) {
              if (SQLGetData(hstmt, 1, SQL_C_CHAR, (SQLPOINTER)sId, 255, &cbId) == SQL_SUCCESS) {
                printf("Id: %s\n", sId);
              }
            }
          }
          SQLFreeHandle(SQL_HANDLE_STMT, hstmt);
        }
        SQLDisconnect(hdbc);
      }
      SQLFreeHandle(SQL_HANDLE_DBC, hdbc);
    }
    SQLFreeHandle(SQL_HANDLE_ENV, henv);
  }