Подскажите альтернативный способ объединения между запросами

...
require 'scripts/connect.php';
$first_name = trim($_REQUEST['first_name']);
$name = trim($_REQUEST['name']);
$last_name = trim($_REQUEST['last_name']);
 
$sql_select = "SELECT * FROM table1 WHERE first_name='$first_name' OR name='$name' OR last_name='$last_name'
UNION
SELECT * FROM table2 WHERE first_name='$first_name' OR name='$name' OR last_name='$last_name'
UNION
SELECT * FROM table3 WHERE first_name='$first_name' OR name='$name' OR last_name='$last_name'
";
 
$result = mysql_query($sql_select);
$row = mysql_fetch_array($result);
?>
<?php do { ?>
<center>
<table border=1> 
<tr>
<td>
<?php echo $row['first_name'];?>
&nbsp;
<?php echo $row['name'];?>
&nbsp;
<?php echo $row['last_name'];?>
</td>
...

$sql_select = "SELECT * FROM table1 WHERE table1.first_name='$first_name' || table1.last_name='$last_name' || table1.otch_name='$otch_name'
UNION
SELECT * FROM table2 WHERE table2.first_name='$first_name' || table2.last_name='$last_name' || table2.otch_name='$otch_name'
UNION
SELECT * FROM table3 WHERE table3.first_name='$first_name' || table3.last_name='$last_name' || table3.otch_name='$otch_name'
";