This example demonstrates a SELECT statement with a group of numeric columns, being converted into a null terminated string. It is a useful technique when there is a need to read and write number, which are larger than 16 digits. Also, this example demonstrates the overriding of datetime columns.
#include <iostream> using namespace std; #include <stdio.h>
#define OTL_ODBC // Compile OTL 4.0/ODBC
#include <otlv4.h> // include the OTL 4.0 header file
otl_connect db; // connect object
void insert()
// insert rows into table
{
otl_stream o(50, // buffer size
"insert into test_tab values(12345678900000000+convert(numeric,:f1<int>),:f11<int>,:f2<char[31]>, GETDATE())",
// SQL statement
db // connect object
);
char tmp[32];
for(int i=1;i<=100;++i){
sprintf(tmp,"Name%d",i);
o<<i<<i<<tmp;
}
}
void select()
{
otl_stream i;
i.set_all_column_types(otl_all_num2str | otl_all_date2str);
// map all numeric columns to strings as well as
// map all date columns to strings
i.open(50, // buffer size
"select * from test_tab "
"where f1>=12345678900000000+convert(numeric,:f11<int>) "
" and f1<=12345678900000000+convert(numeric,:f12<int>)*2",
// SELECT statement
db // connect object
);
// create select stream
char f1[40];
char f11[40];
char f2[31];
char f3[40];
i<<8<<8;
// SELECT automatically executes when all input variables are
// assigned. First portion of output rows is fetched to the buffer
while(!i.eof()){ // while not end-of-data
i>>f1>>f11>>f2>>f3;
cout<<"f1="<<f1<<", f11="<<f11<<", f2="<<f2<<", f3="<<f3<<endl;
}
i<<4<<4;
// SELECT automatically executes when all input variables are
// assigned. First portion of output rows is fetched to the buffer
while(!i.eof()){ // while not end-of-data
i>>f1>>f11>>f2>>f3;
cout<<"f1="<<f1<<", f11="<<f11<<", f2="<<f2<<", f3="<<f3<<endl;
}
}
int main()
{
otl_connect::otl_initialize(); // initialize ODBC environment
try{
db.rlogon("scott/tiger@mssql"); // connect to ODBC
otl_cursor::direct_exec
(
db,
"drop table test_tab",
otl_exception::disabled // disable OTL exceptions
); // drop table
otl_cursor::direct_exec
(
db,
"create table test_tab(f1 numeric, f11 int, f2 varchar(30), f3 datetime)"
); // create table
insert(); // insert records into table
select(); // select records from table
}
catch(otl_exception& p){ // intercept OTL exceptions
cerr<<p.msg<<endl; // print out error message
cerr<<p.stm_text<<endl; // print out SQL that caused the error
cerr<<p.var_info<<endl; // print out the variable that caused the error
}
db.logoff(); // disconnect from ODBC
return 0;
}
f1=12345678900000008, f11=8, f2=Name8, f3=2001-02-03 21:29:49.560 f1=12345678900000009, f11=9, f2=Name9, f3=2001-02-03 21:29:49.560 f1=12345678900000010, f11=10, f2=Name10, f3=2001-02-03 21:29:49.560 f1=12345678900000011, f11=11, f2=Name11, f3=2001-02-03 21:29:49.560 f1=12345678900000012, f11=12, f2=Name12, f3=2001-02-03 21:29:49.560 f1=12345678900000013, f11=13, f2=Name13, f3=2001-02-03 21:29:49.560 f1=12345678900000014, f11=14, f2=Name14, f3=2001-02-03 21:29:49.560 f1=12345678900000015, f11=15, f2=Name15, f3=2001-02-03 21:29:49.560 f1=12345678900000016, f11=16, f2=Name16, f3=2001-02-03 21:29:49.560 f1=12345678900000004, f11=4, f2=Name4, f3=2001-02-03 21:29:49.560 f1=12345678900000005, f11=5, f2=Name5, f3=2001-02-03 21:29:49.560 f1=12345678900000006, f11=6, f2=Name6, f3=2001-02-03 21:29:49.560 f1=12345678900000007, f11=7, f2=Name7, f3=2001-02-03 21:29:49.560 f1=12345678900000008, f11=8, f2=Name8, f3=2001-02-03 21:29:49.560
Copyright © 1996, 2007, Sergei Kuchin, email: skuchin@ispwest.com, skuchin@gmail.com.
Permission to use, copy, modify and redistribute this document for any purpose is hereby granted without fee, provided that the above copyright notice appear in all copies.