EXAMPLE4.C

/*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) 
intargc; 
char*argv[]; 
{ 
/* Here are the variables which will be used to store the 
* data being examined. 
*/ 
DBCHARname[MAXNAME+1];/* MAXNAME is defined in 
* "sqldb.h" as the maximum 
* length for names of database 
* objects, such as tables, 
* columns, and procedures. 
*/ 
DBCHARtype[TYPELEN+1]; 
DBINTid; 
 
DBCHARdatebuf[64]; 
DBINTlen; 
charnumstring[32]; 
intquitflag = 0; 
RETCODErow_code; 
DBINTrownum; 
 
        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; 
intseverity; 
intdberr; 
intoserr; 
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; 
DBINTmsgno; 
intmsgstate; 
intseverity; 
char*msgtext; 
{ 
printf 
("SQL Server message %ld, state %d, severity %d:\n\t%s\n", 
msgno, msgstate, severity, msgtext); 
return(0); 
}