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/*
* testlibpq5.cc
* Test the C++ version of LIBPQ, the POSTGRES frontend library.
* tests the binary cursor interface
*
*
*
populate a database by doing the following (use testlibpq5.sql):
CREATE TABLE test1 (i int4, d float4, p polygon);
INSERT INTO test1 values (1, 3.567, '(3.0, 4.0, 1.0, 2.0)'::polygon);
INSERT INTO test1 values (2, 89.05, '(4.0, 3.0, 2.0, 1.0)'::polygon);
the expected output is:
tuple 0: got
i = (4 bytes) 1,
d = (4 bytes) 3.567000,
p = (4 bytes) 2 points boundbox = (hi=3.000000/4.000000, lo = 1.000000,2.000000)
tuple 1: got
i = (4 bytes) 2,
d = (4 bytes) 89.050003,
p = (4 bytes) 2 points boundbox = (hi=4.000000/3.000000, lo = 2.000000,1.000000)
*
*/
#include <iostream.h>
#include "libpq++.h"
#include <stdlib.h>
extern "C"
{
#include "postgres.h" // for Postgres types
#include "utils/geo_decls.h" // for the POLYGON type
}
int main()
{
// Begin, by connecting to the backend using hardwired constants
// and a test database created by the user prior to the invokation
// of this test program. Connect using cursor interface.
const char* dbName = "dbname=template1"; // change this to the name of your test database
PgCursor data(dbName, "mycursor");
// check to see that the backend connection was successfully made
if ( data.ConnectionBad() )
{
cerr << "Connection to database '" << dbName << "' failed." << endl
<< data.ErrorMessage();
exit(1);
}
// Declare a binary cursor for all the tuples in database 'test1'
if ( !data.Declare("select * from test1", 1) )
{
cerr << "DECLARE CURSOR command failed" << endl;
exit(1);
}
// fetch all instances from the current cursor
if ( !data.Fetch() )
{
cerr << "FETCH ALL command didn't return tuples properly" << endl;
exit(1);
}
// Find the field numbers for the columns 'i', 'd', and 'p'
int i_fnum = data.FieldNum("i");
int d_fnum = data.FieldNum("d");
int p_fnum = data.FieldNum("p");
/*
for (i=0;i<3;i++) {
printf("type[%d] = %d, size[%d] = %d\n",
i, data.FieldType(i),
i, data.FieldSize(i));
}
*/
// Print out the information about the extracted tuple
for (int i = 0; i < data.Tuples(); i++)
{
// we hard-wire this to the 3 fields we know about
int* ival = (int*)data.GetValue(i, i_fnum);
float* dval = (float*)data.GetValue(i, d_fnum);
int plen = data.GetLength(i, p_fnum);
// Allocate correct memory space for the Polygon struct and copy
// the extracted data into it.
// plen doesn't include the length field so need to increment by VARHDSZ
POLYGON* pval = (POLYGON*) malloc(plen + VARHDRSZ);
pval->size = plen;
memmove((char*)&pval->npts, data.GetValue(i, p_fnum), plen);
// Display Polygon Information
cout << "tuple " << i << ": got" << endl
<< " i = (" << data.GetLength(i, i_fnum) << " bytes) " << *ival << "," << endl
<< " d = (" << data.GetLength(i, d_fnum) << " bytes) " << *dval << "," << endl
<< " p = (" << data.GetLength(i, d_fnum) << " bytes) " << pval->npts << " points"
<< "\tboundbox = (hi=" << pval->boundbox.high.x << "/" << pval->boundbox.high.y << ","
<< "lo = " << pval->boundbox.low.x << "," << pval->boundbox.low.y << ")" << endl;
// Deallocate memory allocated for the Polygon structure
free(pval);
}
return 0;
}
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