#include <iostream.h> #include <stdio.h>
#define OTL_DB2_CLI // Compile OTL 4.0/DB2-CLI
#define OTL_STL // turn on OTL in the STL compliance mode
#define OTL_STREAM_POOLING_ON
// turn on OTL stream pooling.
// #define OTL_STREAM_POOLING_ON line
// can be commented out, the number of iteration in
// the select() loop can be increased, and the difference
// in performace with and without OTL_STREAM_POOLING_ON can
// be benchmarked. The difference should grow with the overall
// number of streams to be used in one program.
#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(:f1<int>,:f2<char[31]>)",
// SQL statement
db // connect object
);
char tmp[32];
for(int i=1;i<=100;++i){
sprintf(tmp,"Name%d",i);
o<<i<<tmp;
}
#ifdef OTL_STREAM_POOLING_ON
o.close(false); // do not save the stream in the stream pool.
// in other words, destroy it on the spot, since
// the stream is not going to be reused later.
#else
o.close();
#endif
}
void select()
{ // when this function is called in a loop,
// on the second iteration of the loop the streams i1, i2 will
// will get the instances of the OTL stream from the stream
// pool, "fast reopen", so to speak.
otl_stream i1(50, // buffer size
"select * from test_tab where f1>=:f11<int> and f1<=:f12<int>*2",
// SELECT statement
db // connect object
);
// create select stream
otl_stream i2(33, // buffer size
"select f1,f2 from test_tab where f1>=:f11<int> and f1<=:f12<int>*2",
// SELECT statement
db // connect object
);
// create select stream
// i1 and i2 are NOT similar, because their buffer sizes as well
// as SQL statements are not equal. It will generate two entry points in the
// OTL stream pool.
int f1;
char f2[31];
i1<<2<<2; // assigning :f11 = 2, :f12 = 2
// SELECT automatically executes when all input variables are
// assigned. First portion of output rows is fetched to the buffer
while(!i1.eof()){ // while not end-of-data
i1>>f1>>f2;
cout<<"I1==> f1="<<f1<<", f2="<<f2<<endl;
}
i2<<3<<3; // assigning :f11 = 2, :f12 = 2
// SELECT automatically executes when all input variables are
// assigned. First portion of output rows is fetched to the buffer
while(!i2.eof()){ // while not end-of-data
i2>>f1>>f2;
cout<<"I2==> f1="<<f1<<", f2="<<f2<<endl;
}
} // destructors of i1, i2 will call the close()
// function for both of the streams and the OTL stream
// instances will be placed in the stream pool.
int main()
{
otl_connect::otl_initialize(); // initialize the environment
try{
db.rlogon("scott/tiger@db2sql"); // connect to the database
#ifdef OTL_STREAM_POOLING_ON
db.set_stream_pool_size(2);
// set the maximum stream pool size and actually initializes
// the stream pool.
// if this function is not called, the stream pool
// gets initialized anyway, with the default size of 32 entries.
#endif
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 int, f2 varchar(30))"
); // create table
insert(); // insert records into table
for(int i=1;i<=10; ++i){
cout<<"===================> Iteration: "<<i<<endl;
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 the database
return 0;
}
===================> Iteration: 1 I1==> f1=2, f2=Name2 I1==> f1=3, f2=Name3 I1==> f1=4, f2=Name4 I2==> f1=3, f2=Name3 I2==> f1=4, f2=Name4 I2==> f1=5, f2=Name5 I2==> f1=6, f2=Name6 ===================> Iteration: 2 I1==> f1=2, f2=Name2 I1==> f1=3, f2=Name3 I1==> f1=4, f2=Name4 I2==> f1=3, f2=Name3 I2==> f1=4, f2=Name4 I2==> f1=5, f2=Name5 I2==> f1=6, f2=Name6 ===================> Iteration: 3 I1==> f1=2, f2=Name2 I1==> f1=3, f2=Name3 I1==> f1=4, f2=Name4 I2==> f1=3, f2=Name3 I2==> f1=4, f2=Name4 I2==> f1=5, f2=Name5 I2==> f1=6, f2=Name6 ===================> Iteration: 4 I1==> f1=2, f2=Name2 I1==> f1=3, f2=Name3 I1==> f1=4, f2=Name4 I2==> f1=3, f2=Name3 I2==> f1=4, f2=Name4 I2==> f1=5, f2=Name5 I2==> f1=6, f2=Name6 ===================> Iteration: 5 I1==> f1=2, f2=Name2 I1==> f1=3, f2=Name3 I1==> f1=4, f2=Name4 I2==> f1=3, f2=Name3 I2==> f1=4, f2=Name4 I2==> f1=5, f2=Name5 I2==> f1=6, f2=Name6 ===================> Iteration: 6 I1==> f1=2, f2=Name2 I1==> f1=3, f2=Name3 I1==> f1=4, f2=Name4 I2==> f1=3, f2=Name3 I2==> f1=4, f2=Name4 I2==> f1=5, f2=Name5 I2==> f1=6, f2=Name6 ===================> Iteration: 7 I1==> f1=2, f2=Name2 I1==> f1=3, f2=Name3 I1==> f1=4, f2=Name4 I2==> f1=3, f2=Name3 I2==> f1=4, f2=Name4 I2==> f1=5, f2=Name5 I2==> f1=6, f2=Name6 ===================> Iteration: 8 I1==> f1=2, f2=Name2 I1==> f1=3, f2=Name3 I1==> f1=4, f2=Name4 I2==> f1=3, f2=Name3 I2==> f1=4, f2=Name4 I2==> f1=5, f2=Name5 I2==> f1=6, f2=Name6 ===================> Iteration: 9 I1==> f1=2, f2=Name2 I1==> f1=3, f2=Name3 I1==> f1=4, f2=Name4 I2==> f1=3, f2=Name3 I2==> f1=4, f2=Name4 I2==> f1=5, f2=Name5 I2==> f1=6, f2=Name6 ===================> Iteration: 10 I1==> f1=2, f2=Name2 I1==> f1=3, f2=Name3 I1==> f1=4, f2=Name4 I2==> f1=3, f2=Name3 I2==> f1=4, f2=Name4 I2==> f1=5, f2=Name5 I2==> f1=6, f2=Name6
Copyright © 1996, 2001, Sergei Kuchin, email: skuchin@sprynet.com, kuchin@hotmail.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.