indexeddbviewexample.htm

The goal of this library is to make ODBC recordsets look just like an STL container. As a user, you

<pre><code><span class="codeComment">// &quot;Example&quot; class to hold rows from our database table</span>
class Example
{
  public:                                        <span class="codeComment">// tablename.columnname:</span>
	int exampleInt;                         <span class="codeComment">// DB_EXAMPLE.INT_VALUE</span>
	string exampleStr;                      <span class="codeComment">// DB_EXAMPLE.STRING_VALUE</span>
	double exampleDouble;                   <span class="codeComment">// DB_EXAMPLE.DOUBLE_VALUE</span>
	long exampleLong;                       <span class="codeComment">// DB_EXAMPLE.EXAMPLE_LONG</span>
	TIMESTAMP_STRUCT exampleDate;           <span class="codeComment">// DB_EXAMPLE.EXAMPLE_DATE</span>

	Example(int exInt, const string &amp;exStr, double exDouble, long exLong,
		const TIMESTAMP_STRUCT &amp;exDate) :
	   exampleInt(exInt), exampleStr(exStr), exampleDouble(exDouble), exampleLong(exLong),
	   exampleDate(exDate)
	{ }

};

<span class="codeComment">// Parameter object to hold parameters for dynamic SQL query below </span>
class ParamObjExample
{
    public:
	int lowIntValue;
	int highIntValue;
	string strValue;
	TIMESTAMP_STRUCT dateValue;
};

<span class="codeComment">// Create an association between table columns and fields in our object</span>
class BCAExampleObj
{
public:
	void operator()(BoundIOs &amp;boundIOs, Example &amp;rowbuf)
    {
	   boundIOs[&quot;INT_VALUE&quot;]	== rowbuf.exampleInt;
	   boundIOs[&quot;STRING_VALUE&quot;]	== rowbuf.exampleStr;
	   boundIOs[&quot;DOUBLE_VALUE&quot;]	== rowbuf.exampleDouble;
	   boundIOs[&quot;EXAMPLE_LONG&quot;]	== rowbuf.exampleLong;
	   boundIOs[&quot;EXAMPLE_DATE&quot;]	== rowbuf.exampleDate;
	}
};

<span class="codeComment">// Create an association between query parameters and fields in our parameters object</span>
class BPAExampleObj
{
public:
	void operator()(BoundIOs &amp;boundIOs, ParamObjExample &amp;paramObj)
	{
	  boundIOs[0] == paramObj.lowIntValue;
	  boundIOs[1] == paramObj.highIntValue;
	  boundIOs[2] == paramObj.strValue;
	  boundIOs[3] == paramObj.dateValue;
	}

};

<span class="codeComment">// Set parameters function for Example ... used by IndexedDBView&lt;Example&gt; to set dynamic query parameters
// Dynamic query parameters are indicated by (?) in our query string for the IndexedDBView</span>
void SetParamsExample(ParamObjExample &amp;params)
{
	<span class="codeComment">// set parameter values</span>
	params.lowIntValue = 2;
	params.highIntValue = 8;
	params.strValue = &quot;Example&quot;;
	
	TIMESTAMP_STRUCT paramDate = {2000, 1, 1, 0, 0, 0, 0};
	params.dateValue = paramDate;
}


<span class="codeComment">// Example of using an IndexDBView to read, insert and update records in a container / database</span>
void IndexedViewExample()
{
	typedef DBView&lt;Example, ParamObjExample&gt; DBV;

	DBV view(&quot;DB_EXAMPLE&quot;,   BCAExampleObj(), 
	  &quot;WHERE INT_VALUE BETWEEN (?) AND (?) OR &quot;
	  &quot;STRING_VALUE = (?) OR EXAMPLE_DATE &lt;= (?) ORDER BY EXAMPLE_LONG&quot;,
	  BPAExampleObj());

	IndexedDBView&lt;DBV&gt; indexed_view(view, &quot;UNIQUE PrimaryIndex; STRING_VALUE; AlternateIndex; EXAMPLE_LONG, EXAMPLE_DATE&quot;, 
	  BOUND, USE_ALL_FIELDS, cb_ptr_fun(SetParamsExample));
   		

	<span class="codeComment">// Find the item where the STRING_VALUE matches the string &quot;Foozle&quot;</span>
	IndexedDBView&lt;DBV&gt;::indexed_iterator idxview_it = indexed_view.find(string(&quot;Foozle&quot;));
		

	<span class="codeComment">// Update the item with the key of &quot;Foozle&quot;, to read &quot;Fizzle&quot; instead</span>
	if (idxview_it != indexed_view.end()) {
		Example replacement;
		replacement = *idxview_it;
		replacement.exampleStr = &quot;Fizzle&quot;;
		indexed_view.replace(idxview_it, replacement);
	}

	<span class="codeComment">// 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.</span>
	const TIMESTAMP_STRUCT date_criteria = {2000, 1, 1, 0, 0, 0, 0};
	long long_criteria = 33;
	IndexedDBView&lt;DBV&gt;::indexed_pair pr = indexed_view.equal_range_AK (&quot;AlternateIndex&quot;, long_criteria, date_criteria);

	idxview_it = pr.first;

	cout &lt;&lt; &quot;*** Size before erase calls: &quot; &lt;&lt; indexed_view.size() &lt;&lt; &quot; ***&quot;
	&lt;&lt; endl;
		
	<span class="codeComment">// Remove all items that match the criteria in our equal_range_AK lookup</span>
	while (idxview_it != pr.second)
	{
		<span class="codeComment">// 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.</span>
		IndexedDBView&lt;DBV&gt;::indexed_iterator deleteMe = idxview_it;

		idxview_it++;

		indexed_view.erase(deleteMe);

	}

	cout &lt;&lt; &quot;*** Size after erase calls: &quot; &lt;&lt; indexed_view.size() &lt;&lt; &quot; ***&quot;
			&lt;&lt; endl;


	<span class="codeComment">// Finally, insert a new item into the container</span>
	pair&lt;IndexedDBView&lt;DBV&gt;::iterator, bool&gt; ins_pr;

	ins_pr = indexed_view.insert(Example(459, &quot;Unique String #1&quot;, 3.4, 1, date_criteria));

	cout &lt;&lt; &quot;insertion succeded = &quot; &lt;&lt; (ins_pr.second == true ? &quot;true&quot;: &quot;false&quot;) &lt;&lt; endl;

}
</code></pre>