OTL4, Example 768 (PostgreSQL 9.5 UPSERT,  otl_read_row() and otl_write_row())

This example demonstrates how to use PostgreSQL 9.5's UPSERT, and OTL template otl_read_row() / otl_write_row() functions.

Source Code

#include <iostream>
#include <thread>
using namespace std;

#include <stdio.h>
// #define OTL_ODBC_UNIX // uncomment this line if UnixODBC is used
#define OTL_ODBC_ALTERNATE_RPC
#if !defined(_WIN32) && !defined(_WIN64)
#define OTL_ODBC
#else
#define OTL_ODBC_POSTGRESQL // required with PG ODBC on Windows
#endif
#include <otlv4.h> // include the OTL 4.0 header file

otl_connect db; // connect object

void insert(void)
// insert rows into table
{
otl_stream o(10, // stream buffer size in logical rows.
"insert into test_tab "
"values(:f1<int>,:f2<char[31]>)",
// INSERT statement
db // connect object
);
// Write rows into the stream. At the end of each row, check for
// "end-of-row" condition.
otl_write_row(o,1,"Line1");
otl_write_row(o,2,"Line21");

// the old way (operators >>() / <<()) is available as always:
// o<<1<<"Line1";
// o<<2<<"Line21";

o.flush();
}

void upsert(void)
// "upsert" rows into table
{
otl_stream o(10, // stream buffer size in logical rows.
"insert into test_tab (f1,f2) "
"values(:f1<int>,:f2<char[31]>) "
"on conflict (f1) "
"do update set f2=:f22<char[31]>||'--'||excluded.f1 ",
// "UPSERT" statement
db // connect object
);
// Write rows into the stream. At the end of each row, check for
// "end-of-row" condition.
otl_write_row(o,2,"Line22","Line22");
otl_write_row(o,3,"Line3","Line3");

// the old way (operators >>() / <<()) is available as always:
// o<<1<<"Line1";
// o<<2<<"Line21";

o.flush();
}


void select(void)
{
otl_stream i(5, // stream buffer size in logical rows
"select * from test_tab ",
// SELECT statement
db // connect object
);
// SELECT output columns
int f1=0;
char f2[31];

while(!i.eof()){ // while not end-of-data
// Read a row from the stream. Check for the "end-of-row" condition
// at the end each row.
otl_read_row(i,f1,f2);

// The old way (operators >>() / <<()) is available as always:
// i>>f1>>f2;

cout<<"f1="<<f1<<", f2="<<f2<<endl;
}

}


int main()
{
otl_connect::otl_initialize(); // initialize database API environment
try{

db.rlogon("scott/tiger@postgresql"); // connect to the database

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

db<<"create unique index ind001 on test_tab(f1)";
// create unique index

insert(); // insert records into table
upsert(); // merge 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.sqlstate<<endl; // print out SQLSTATE message
cerr<<p.var_info<<endl; // print out the variable that caused the error
}

db.logoff(); // disconnect from the database

return 0;

}

Output

f1=1, f2=Line1
f1=2, f2=Line22--2
f1=3, f2=Line3

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Copyright 1996-2017, Sergei Kuchin, email: skuchin@gmail.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. THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.