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<TITLE>OTL 4.0, Example 18 (otl_stream and NULLs)</TITLE>
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<H1 ALIGN=CENTER>OTL 4.0, Example 34 (otl_stream and NULLs)</H1>
<H1><A NAME="example1"></A>Example 34 (otl_stream and NULLs)</H1>
<P>This example demonstrates the otl_stream with NULLs.</P>
<H2>Source Code</H2>
<PRE>#include <iostream>
using namespace std;
#include <stdio.h></PRE>
<PRE>#define OTL_ODBC // Compile OTL 4.0/ODBC
#include <otlv4.h> // include the OTL 4.0 header file
<A HREF="otl3_connect_class.htm">otl_connect</A> db; // connect object
void insert()
// insert rows into table
{
<A HREF="otl3_stream_class.htm">otl_stream</A> o(50, // buffer size
"insert into test_tab values(:f1<float>,:f2<char[31]>)",
// SQL statement
db // connect object
);
char tmp[32];
for(int i=1;i<=100;++i){
sprintf(tmp,"Name%d",i);
if(i==10)
o<<(float)i<<<A HREF="otl3_stream_class.htm#otl_null">otl_null</A>();
else
o<<(float)i<<tmp;
}
}
void select()
{
<A HREF="otl3_stream_class.htm">otl_stream</A> i(50, // buffer size
"select * from test_tab where f1>=:f11<int> and f1<=:f12<int>*2",
// SELECT statement
db // connect object
);
// create select stream
float f1;
char f2[31];
i<<8<<8; // assigning :f11 = 8, :f12=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;
if(i.is_null())
cout<<"f1=NULL,";
else
cout<<"f1="<<f1<<",";
i>>f2;
if(i.is_null())
cout<<"f2=NULL";
else
cout<<"f2="<<f2;
cout<<endl;
}
}
int main()
{
<A HREF="otl3_connect_class.htm">otl_connect::otl_initialize</A>(); // initialize ODBC environment
try{
db.rlogon("scott/tiger@mssql"); // connect to ODBC
<A HREF="otl3_const_sql.htm">otl_cursor::direct_exec
</A> (
db,
"drop table test_tab",
otl_exception::disabled // disable OTL exceptions
); // drop table
<A HREF="otl3_const_sql.htm">otl_cursor::direct_exec
</A> (
db,
"create table test_tab(f1 int, f2 varchar(30))"
); // create table
insert(); // insert records into table
select(); // select records from table
}
catch(<A HREF="otl3_exception_class.htm">otl_exception</A>& 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.sqlstate<<endl; // print out SQLSTATE message
cerr<<p.var_info<<endl; // print out the variable that caused the error
}
db.logoff(); // disconnect from ODBC
return 0;
}
</PRE>
<H2>Output</H2>
<PRE>f1=8, f2=Name8
f1=9, f2=Name9
f1=10, f2=NULL
f1=11, f2=Name11
f1=12, f2=Name12
f1=13, f2=Name13
f1=14, f2=Name14
f1=15, f2=Name15
f1=16, f2=Name16
<HR WIDTH="100%"></PRE>
<CENTER><P><A HREF="otl3_examples.htm">Examples</A> <A HREF="otl3.htm">Contents</A>
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<P>Copyright © 1996, 2008, Sergei Kuchin, email: <A HREF="mailto:skuchin@aceweb.com">skuchin@aceweb.com</A>,
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<P><I>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. </I></P>
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