MDAC 2.5 SDK - ODBC Programmer's Reference
Appendix F: ODBC Cursor Library

Cursor Library Code Example

The following example uses the cursor library to retrieve each order's ID, open date, and status from the ORDERS table. It then displays 20 rows of data. If the user updates this data, the code updates the rowset buffers and executes a positioned update statement. Finally, it prompts the user for the direction to scroll and repeats the process.

#define ROWS 20
#define STATUS_LEN 6
#define OPENDATE_LEN 11
#define DONE -1

SQLHENV        henv;
SQLHDBC        hdbc;
SQLHSTMT       hstmt1, hstmt2;
SQLRETURN      retcode;
SQLCHAR        szStatus[ROWS][STATUS_LEN], 
               szOpenDate[ROWS][OPENDATE_LEN];
SQLCHAR        szNewStatus[STATUS_LEN], szNewOpenDate[OPENDATE_LEN];
SQLSMALLINT    sOrderID[ROWS], sNewOrderID[ROWS];
SQLINTEGER     cbStatus[ROWS], cbOrderID[ROWS], cbOpenDate[ROWS];
SQLUINTEGER    FetchOrientation, crow, FetchOffset, irowUpdt;
SQLUSMALLINT   RowStatusArray[ROWS];

SQLAllocHandle(SQL_HANDLE_ENV, SQL_NULL_HANDLE, &henv);
SQLSetEnvAttr(henv, SQL_ATTR_ODBC_VERSION, SQL_OV_ODBC3,0);
SQLAllocHandle(SQL_HANDLE_DBC, henv, &hdbc);

/* Specify that the ODBC Cursor Library is always used, then connect. */

SQLSetConnectAttr(hdbc, SQL_ATTR_ODBC_CURSORS, SQL_CUR_USE_ODBC);
SQLConnect(hdbc, "SalesOrder", SQL_NTS,
            "JohnS", SQL_NTS,
            "Sesame", SQL_NTS);

if (retcode == SQL_SUCCESS || retcode == SQL_SUCCESS_WITH_INFO) {

   /* Allocate a statement handle for the result set and a statement */
   /* handle for positioned update statements. */

   SQLAllocHandle(SQL_HANDLE_STMT, hdbc, &hstmt1);
   SQLAllocHandle(SQL_HANDLE_STMT, hdbc, &hstmt2);

   /* Specify an updatable static cursor with 20 rows of data. Set */
   /* the cursor name, execute the SELECT statement, and bind the */
   /* rowset buffers to result set columns in column-wise fashion. */
   SQLSetStmtAttr(hstmt1, SQL_ATTR_CONCURRENCY, SQL_CONCUR_VALUES, 0);
   SQLSetStmtAttr(hstmt1, SQL_ATTR_CURSOR_TYPE, SQL_CURSOR_STATIC, 0);
   SQLSetStmtAttr(hstmt1, SQL_ATTR_ROW_ARRAY_SIZE, ROWS, 0);
   SQLSetStmtAttr(hstmt1, SQL_ATTR_ROW_STATUS_PTR, RowStatusArray, 0);
   SQLSetStmtAttr(hstmt1, SQL_ATTR_ROWS_FETCHED_PTR, &crow, 0);
   SQLSetCursorName(hstmt1, "ORDERCURSOR", SQL_NTS);
   SQLExecDirect(hstmt1,
                  "SELECT ORDERID, OPENDATE, STATUS FROM ORDERS ",
                  SQL_NTS);
   SQLBindCol(hstmt1, 1, SQL_C_SSHORT, sOrderID, 0, cbName);
   SQLBindCol(hstmt1, 2, SQL_C_CHAR, szOpenDate, OPENDATE_LEN, cbOpenDate);
   SQLBindCol(hstmt1, 3, SQL_C_CHAR, szStatus, STATUS_LEN, cbStatus);

   /* Fetch the first block of data and display it. Prompt the user */
   /* for new data values. If the user supplies new values, update */
   /* the rowset buffers, bind them to the parameters in the update */
   /* statement, and execute a positioned update on another hstmt. */
   /* Prompt the user for how to scroll. Fetch and redisplay data as */
   /* needed. */

   FetchOrientation = SQL_FETCH_FIRST;
   FetchOffset = 0;
   do {

      SQLFetchScroll(hstmt1, FetchOrientation, FetchOffset);
      DisplayRows(sOrderID, szOpenDate, szStatus, RowStatusArray);

      if (PromptUpdate(&irowUpdt,&sNewOrderID,szNewOpenDate,szNewStatus)==TRUE){
         sOrderID[irowUpdt] = sNewOrderID;
         cbOrderID[irowUpdt] = 0;
         strcpy(szOpenDate[irowUpdt], szNewOpenData);
         cbOpenDate[irowUpdt] = SQL_NTS;
         strcpy(szStatus[irowUpdt], szNewStatus);
         cbStatus[irowUpdt] = SQL_NTS;
         SQLBindParameter(hstmt2, 1, SQL_PARAM_INPUT,
                           SQL_C_SSHORT, SQL_INTEGER, 0, 0,
                           &sOrderID[irowUpdt], 0, &cbOrderID[irowUpdt]);
         SQLBindParameter(hstmt2, 2, SQL_PARAM_INPUT,
                           SQL_C_CHAR, SQL_TYPE_DATE, OPENDATE_LEN, 0,
                           szOpenDate[irowUpdt], OPENDATE_LEN, &cbOpenDate[irowUpdt]);
         SQLBindParameter(hstmt2, 3, SQL_PARAM_INPUT,
                           SQL_C_CHAR, SQL_CHAR, STATUS_LEN, 0,
                           szStatus[irowUpdt], STATUS_LEN, &cbStatus[irowUpdt]);
         SQLExecDirect(hstmt2,
                        "UPDATE EMPLOYEE SET ORDERID = ?, OPENDATE = ?, STATUS = ?"
                        "WHERE CURRENT OF EMPCURSOR",
                        SQL_NTS);
      }

   while (PromptScroll(&FetchOrientation, &FetchOffset) != DONE)
}