dtl

// Using a DynamicIndexedDBView to read, update and insert records in a database.

// Dynamic IndexedDBView example

// ... classes as in IndexedDBView example  ....

void DynamicIndexedViewExample()
{
 DynamicDBView<ParamObjExample> dynamic_view("DB_EXAMPLE",
	 "INT_VALUE, STRING_VALUE, DOUBLE_VALUE, EXAMPLE_LONG,  EXAMPLE_DATE",
	 "WHERE INT_VALUE BETWEEN (?) AND (?) OR "
	  "STRING_VALUE = (?) OR EXAMPLE_DATE <= (?) ORDER BY EXAMPLE_LONG",
	  BPAExampleObj());

 DynamicIndexedDBView< DynamicDBView<ParamObjExample> >  
	 indexed_view(dynamic_view, 
         "UNIQUE PrimaryIndex; STRING_VALUE;"
         "IndexLongDate; EXAMPLE_LONG, EXAMPLE_DATE",
	 BOUND, USE_ALL_FIELDS, cb_ptr_fun(SetParamsExample));

 // Find the item where the STRING_VALUE matches the string  "Foozle"
 DynamicIndexedDBView< DynamicDBView<ParamObjExample> >::iterator idxview_it =  indexed_view.find(string("Foozle"));


 // Update the item with the key of "Foozle", to read  "Fizzle" instead
 if (idxview_it != indexed_view.end()) {
  variant_row replacement;
  replacement = *idxview_it;
  replacement["STRING_VALUE"] =   string("Fizzle");
  indexed_view.replace(idxview_it, replacement);
 }

 // Now find a second set of items using AlternateIndex
 // The STL convention for equal_range is to return a pair  consisting of: 
 // 1. an iterator referring to the beginning of the list of found  items
 // 2. an iterator pointing to the end of the list of found items. 
 // We will remove all items in this range.
 const TIMESTAMP_STRUCT date_criteria = {2000, 1, 1, 0, 0, 0, 0};
 long long_criteria = 33;
 pair<DynamicIndexedDBView<DynamicDBView<ParamObjExample> >::iterator,
	 DynamicIndexedDBView<DynamicDBView<ParamObjExample> >::iterator>
   	 pr = indexed_view.equal_range_AK("IndexLongDate", long_criteria, date_criteria);

 idxview_it = pr.first;

 cout <<  *** // Remove all rows that matched the criteria in our equal_range_AK lookup 
 while (idxview_it !="pr.second)" { 
   // as iterator is invalidated upon an erase(), use a temporary iterator 
   // to point to DataObj to erase 
   // increment idxview_it before we erase so it will still be valid 
   // when we erase the DataObj 
   DynamicIndexedDBView< DynamicDBView<ParamObjExample> >::iterator deleteMe = idxview_it; 
   idxview_it++; 
   indexed_view.erase(deleteMe); 
 } 
 cout << "*** Size after erase calls: " << indexed_view.size() << " ***" << endl; 
 
 // Finally, insert a new item into the container 
 pair<DynamicIndexedDBView< DynamicDBView<ParamObjExample> >::iterator, bool> ins_pr; 
 
 variant_row r(indexed_view.GetDataObj()); 
 r["INT_VALUE"]=459; 
 r["STRING_VALUE"]=string("Unique String #1"); 
 r["DOUBLE_VALUE"]=3.5; 
 r["EXAMPLE_LONG"]=1; 
 r["EXAMPLE_DATE"]=date_criteria; 
 ins_pr=indexed_view.insert(r);
 cout << "insertion succeded=" <<  (ins_pr.second == true ? " true": " false") << endl; 
}

Copyright © 2002, Michael Gradman and Corwin Joy.

Permission to use, copy, modify, distribute and sell this software and its documentation for any purpose is hereby granted without fee, provided that the above copyright notice appears in all copies and that both that copyright notice and this permission notice appear in supporting documentation. Corwin Joy and Michael Gradman make no representations about the suitability of this software for any purpose. It is provided "as is" without express or implied warranty.

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