/*
* PROGRAM: Object oriented API samples.
* MODULE: 02.update.cpp
* DESCRIPTION: Run once prepared statement with parameters
* a few times, committing transaction after each run.
* Learns how to prepare statement, manually define parameters
* for it, execute that statement with different parameters
* and perform non-default error processing.
*
* Example for the following interfaces:
* IAttachment - database attachment
* ITransaction - transaction
* IStatement - SQL statement execution
* IMessageMetadata - describe input and output data format
* IMetadataBuilder - tool to modify/create metadata
* IStatus - return state holder
*
* Note that all updates are rolled back in this version. (see *** later)
*
* The contents of this file are subject to the Interbase Public
* License Version 1.0 (the "License"); you may not use this file
* except in compliance with the License. You may obtain a copy
* of the License at http://www.Inprise.com/IPL.html
*
* Software distributed under the License is distributed on an
* "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, either express
* or implied. See the License for the specific language governing
* rights and limitations under the License.
*
* The Original Code was created by Inprise Corporation
* and its predecessors. Portions created by Inprise Corporation are
* Copyright (C) Inprise Corporation.
*
* All Rights Reserved.
* Contributor(s): ______________________________________.
* Alex Peshkov, 2013
*/
#include "ifaceExamples.h"
static IMaster* master = fb_get_master_interface();
int get_input(char*, double*);
static const char* Dept_data[] =
{"622", "100", "116", "900", 0};
static double Percent_data[] =
{0.05, 1.00, 0.075, 0.10, 0};
int Input_ptr = 0;
int main()
{
int rc = 0;
// set default password if none specified in environment
setenv("ISC_USER", "sysdba", 0);
setenv("ISC_PASSWORD", "masterkey", 0);
// status vector and main dispatcher
ThrowStatusWrapper status(master->getStatus());
IProvider* prov = master->getDispatcher();
// declare pointers to required interfaces
IAttachment* att = NULL;
ITransaction* tra = NULL;
// Interface executes prepared SQL statement
IStatement* stmt = NULL;
// Interfaces provides access to format of data in messages
IMessageMetadata* meta = NULL;
// Interface makes it possible to change format of data or define it yourself
IMetadataBuilder* builder = NULL;
const char* updstr =
"UPDATE department SET budget = ? * budget + budget WHERE dept_no = ?";
try
{
// attach employee db
att = prov->attachDatabase(&status, "employee", 0, NULL);
// start transaction
tra = att->startTransaction(&status, 0, NULL);
// prepare statement
stmt = att->prepare(&status, tra, 0, updstr, SAMPLES_DIALECT, 0);
// build metadata
// IMaster creates empty new metadata in builder
builder = master->getMetadataBuilder(&status, 2);
// set required info on fields
builder->setType(&status, 0, SQL_DOUBLE + 1);
builder->setType(&status, 1, SQL_TEXT + 1);
builder->setLength(&status, 1, 3);
// IMetadata should be ready
meta = builder->getMetadata(&status);
// no need in builder any more
builder->release();
builder = NULL;
// allocate buffer on stack
char buffer[256];
unsigned len = meta->getMessageLength(&status);
if (len > sizeof(buffer))
{
throw "Input message length too big - can't continue";
}
// locations of parameters in input message
char* dept_no = &buffer[meta->getOffset(&status, 1)];
double* percent_inc = (double*) &buffer[meta->getOffset(&status, 0)];
// null IDs (set to NOT NULL)
short* flag = (short*)&buffer[meta->getNullOffset(&status, 0)];
*flag = 0;
flag = (short*) &buffer[meta->getNullOffset(&status, 1)];
*flag = 0;
// Get the next department-percent increase input pair.
while (get_input(dept_no, percent_inc))
{
printf("\nIncreasing budget for department: %s by %5.2lf percent.\n",
dept_no, *percent_inc);
// Update the budget.
try
{
stmt->execute(&status, tra, meta, buffer, NULL, NULL);
}
catch (const FbException& error)
{
// Handle exception raised during statement execution
if (error.getStatus()->getErrors()[1] == isc_not_valid)
{
// Don't save the update, if the new budget exceeds the limit.
printf("\tExceeded budget limit -- not updated.\n");
tra->rollbackRetaining(&status);
continue;
}
// Another error - use default handler
throw;
}
// Save each department's update independently.
// *** Change to commitRetaining() to see changes
// *** tra->commitRetaining(&status);
tra->rollbackRetaining(&status);
}
// close interfaces
stmt->free(&status);
stmt = NULL;
meta->release();
meta = NULL;
tra->commit(&status);
tra = NULL;
att->detach(&status);
att = NULL;
}
catch (const FbException& error)
{
// handle error
rc = 1;
char buf[256];
master->getUtilInterface()->formatStatus(buf, sizeof(buf), error.getStatus());
fprintf(stderr, "%s\n", buf);
}
// release interfaces after error caught
if (builder)
builder->release();
if (meta)
meta->release();
if (stmt)
stmt->release();
if (tra)
tra->release();
if (att)
att->release();
prov->release();
status.dispose();
return rc;
}
/*
* Get the department and percent parameters for an example to run.
*/
int get_input (char *dept_no, double *percent)
{
if (Dept_data[Input_ptr] == 0)
return 0;
strcpy(dept_no, Dept_data[Input_ptr]);
if ((*percent = Percent_data[Input_ptr++]) == 0)
return 0;
return 1;
}