bpareaddata.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">//BPA Functor to bind SQL parameters to a data object</span>

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

class ExampleParamObj
{
    public:
       	int lowIntValue;
	int highIntValue;
	string strValue;
	TIMESTAMP_STRUCT dateValue;
};

class BPAParamObj
{
public:
	void operator()(BoundIOs &amp;boundIOs, ExampleParamObj &amp;paramObj)
	{
	  boundIOs[0] == paramObj.lowIntValue;
	  boundIOs[1] == paramObj.highIntValue;
	  boundIOs[2] == paramObj.strValue;
	  boundIOs[3] == paramObj.dateValue;
	}

};

<span class="codeComment">// read some Example objects from the database and return a vector of</span>
<span class="codeComment">// the results, use BPA to set join parameters</span>
vector&lt;Example&gt; ReadData()
{
	vector&lt;Example&gt; results;

	<span class="codeComment">// construct view</span>
	
	DBView&lt;Example, ExampleParamObj&gt;
		view(&quot;DB_EXAMPLE&quot;, BCAExampleObj(),
		&quot;WHERE INT_VALUE BETWEEN (?) AND (?) AND &quot;
		&quot;STRING_VALUE = (?) OR EXAMPLE_DATE &lt; (?) ORDER BY EXAMPLE_LONG&quot;,
		BPAParamObj());

	<span class="codeComment">// loop through query results and add them to our vector</span>
	<span class="codeComment">// in this loop, read_it.GetLastCount() records read from DB</span>

	DBView&lt;Example, ExampleParamObj&gt;::select_iterator read_it = view.begin();

	<span class="codeComment">// set parameter values for the WHERE clause in our SQL query</span>
	read_it.Params().lowIntValue = 2;
	read_it.Params().highIntValue = 8;
	read_it.Params().strValue = &quot;Example&quot;;
	
	TIMESTAMP_STRUCT paramDate = {2000, 1, 1, 0, 0, 0, 0};
	read_it.Params().dateValue = paramDate;

	for ( ; read_it != view.end();  read_it++)
	{
		cout &lt;&lt; &quot;Reading element #&quot; &lt;&lt; read_it.GetLastCount() &lt;&lt; endl;
		results.push_back(*read_it);

		cout &lt;&lt; &quot;read_it-&gt;exampleInt = &quot; &lt;&lt; read_it-&gt;exampleInt &lt;&lt; endl;
		cout &lt;&lt; &quot;read_it-&gt;exampleStr = &quot; &lt;&lt; read_it-&gt;exampleStr &lt;&lt; endl;
		
	}
	
	return results;
}
</code></pre>