Tricks of the Windows Gam…ming Gurus (2nd Edition)/Disc2.iso/msdn_vcb/samples/vc98/sdk/dbmsg/sql/dblib/c/example4/example4.c

C/C++ Source or Header | 1996-04-03 | 4.5 KB | 198 lines

/*    example4.c */
/*
** This example accesses the data within each row without using dbbind()
** and illustrates the use of row buffering.
**
** It runs a query, saves all of the returned rows (up to a maximum
** of 100) using DB-LIBRARY row buffering, and allows the user to
** examine data rows at random.
*/

#if defined(DBNTWIN32)
#include <windows.h>
#endif

#include <stdio.h>
#include <stdlib.h>
#include <sqlfront.h>
#include <sqldb.h>

DBPROCESS    *dbproc;    /* Our connection with SQL Server. */
LOGINREC    *login;    /* Our login information. */

#define TYPELEN 2
#define DATELEN 25

/* Forward declarations of the error handler and message handler.
*/
int err_handler(DBPROCESS*, int, int, int, char*, char*);
int msg_handler(DBPROCESS*, DBINT, int, int, char*);

main(argc, argv)
int    argc;
char    *argv[];
{
    /* Here are the variables which will be used to store the
    * data being examined.
    */
    DBCHAR    name[MAXNAME+1];    /* MAXNAME is defined in
    * "sqldb.h" as the maximum
    * length for names of database
    * objects, such as tables,
    * columns, and procedures.
    */
    DBCHAR    type[TYPELEN+1];
    DBINT    id;

    DBCHAR    datebuf[64];
    DBINT    len;
    char    numstring[32];
    int    quitflag = 0;
    RETCODE    row_code;
    DBINT    rownum;

        dbinit();        /* initialize dblib */

    /* Install the user-supplied error-handling and message-handling
    * functions. They are defined at the bottom of this source file.
    */
    dbmsghandle((DBMSGHANDLE_PROC)msg_handler);
    dberrhandle((DBERRHANDLE_PROC)err_handler);

    /*
    ** Get a LOGINREC structure and fill it with the necessary
    ** login information.
    */

    login = dblogin();
    DBSETLUSER (login, "user");
    DBSETLPWD(login, "my_passwd");
    DBSETLAPP(login, "example4");
    DBSETLVERSION(login, DBVER60);

    dbproc = dbopen(login, "my_server");
    dbcmd(dbproc, "select name, type, id, crdate from sysobjects");
    dbcmd(dbproc, " where type = 'S'");

    /*
        ** Set row buffering to 100 rows, via dbsetopt().
    ** Note that this parameter must be passed as an ASCII string.
    */

    dbsetopt(dbproc, DBBUFFER, "100");
    dbsqlexec(dbproc);
    if (dbresults(dbproc) == SUCCEED)
    {
        /* Read all of the rows into DB-LIBRARY's buffer */
        while ((row_code = dbnextrow(dbproc)) != NO_MORE_ROWS)
        {
            /* If DB-LIBRARY's row buffer is full, throw
            * away the oldest row to allow the newest
            * row to be read in.
            */
            if (row_code == BUF_FULL)
                dbclrbuf(dbproc, (DBINT) 1);
        }

        /* Print out the column headers. */

        puts("NAME                 TYPE DATE                   ID");
        puts("-------------------- ---- ---------------------- ----");


        /* Let the user view any row in the table. */

        printf("Type the number of the row you want to see.\n");
        printf("The first row is number 1.\n");
        printf("Asking for row 0 will terminate the program.\n");

        while (quitflag == 0)
        {
            printf("Row number: ");
            gets(numstring);
            rownum = atoi(numstring);

        if (rownum == 0)
            quitflag = 1;
        else
        {
            /* Print out the requested row. */
            if (dbgetrow(dbproc, rownum) == NO_MORE_ROWS)
                printf
                ("That row is not in the table.\n");
            else
            {
                /* Copy variable-length character data
                * (colname).
                    */

                strncpy
                (name, (DBCHAR *)dbdata(dbproc, 1),
                (len = dbdatlen(dbproc, 1)));

                /* String needs terminating null. */

                name[len] = '\0';

                /* Copy fixed-length character data. */

                strncpy
                (type, (DBCHAR *)dbdata(dbproc, 2),
                (len = dbdatlen(dbproc, 2)));
                type[len] = '\0';

                /* Copy integer data. */
                id = *((DBINT *)dbdata(dbproc, 3));

                /* Convert datetime data to a printable
                * string.
                */

                dbconvert(dbproc, SQLDATETIME, (dbdata(dbproc, 4)),
                (DBINT)-1, SQLCHAR, datebuf, (DBINT)-1);


                printf("%-20s %-4s %-22s %-4ld \n",
                name, type, datebuf, id);
                }
            }
        }
    }

    dbexit();
    return(STDEXIT);
}

int err_handler(dbproc, severity, dberr, oserr, dberrstr, oserrstr)
DBPROCESS    *dbproc;
int    severity;
int    dberr;
int    oserr;
char    *dberrstr;
char    *oserrstr;
{
    printf("DB-LIBRARY error:\n\t%s\n", dberrstr);

    if (oserr != DBNOERR)
        printf("Operating-system error:\n\t%s\n", oserrstr);

    if ((dbproc == NULL) || (DBDEAD(dbproc)))
        return(INT_EXIT);

    return(INT_CANCEL);
}

int msg_handler(dbproc, msgno, msgstate, severity, msgtext)
DBPROCESS    *dbproc;
DBINT    msgno;
int    msgstate;
int    severity;
char    *msgtext;
{
    printf
    ("SQL Server message %ld, state %d, severity %d:\n\t%s\n",
    msgno, msgstate, severity, msgtext);
    return(0);
}