How to how a table with previously collected data in a custom form page?
Yes you can do this. 
First of all you need to fetch the 'Table1' data in top of the form.

$query = db_select('Table1' , 'tb');
    $query-&gt;fields('tb');
    $results = $query-&gt;execute()-&gt;fetchAll();


//table structure

$Details = '&lt;table&gt;&lt;tr&gt;&lt;td style="width:15%;"&gt;&lt;/td&gt;&lt;td style="width:30%;"&gt;Employee Id&lt;/td&gt;&lt;td style="width:10%;"&gt;Employee Name&lt;/td&gt;&lt;/tr&gt;';
    foreach($results as $res)
    {
        $Details .= '&lt;td&gt;'.$res-&gt;empid.'&lt;/td&gt;';
        $Details .= '&lt;td&gt;$'.$res-&gt;empname.'&lt;/td&gt;';  
    }

$form['details'] = array(
        '#type' =&gt; 'item',
        '#markup' =&gt; $Details,
        '#suffix' =&gt; '&lt;/div&gt;'
    );

$form['eid'] = array(
    '#type' =&gt; 'textfield' ,
    '#title' =&gt; t('Employee Id'),
    '#maxlength' =&gt; 45,
    '#required'=&gt; true,
);
$form['ename'] = array(
    '#type' =&gt; 'textfield' ,
    '#title' =&gt; t('Employee Name'),
    '#maxlength' =&gt; 45,
    '#required'=&gt; true,
);  


 $form['submit'] = array(
        '#type' =&gt; 'submit' ,
        '#value' =&gt; 'Submit'
    );