ขอโค้ดตัวอย่าง วิธีการใช้งาน UNION ทีคับ วิธีเอาไปใช้ใช้ยังไง

SELECT Column1 AS A1,Column2 AS A2,... FROM [Table-Name]
UNION
SELECT Column1 AS A3,Column2 AS A4,... FROM [Table-Name]


$data=mysql_fetch_array($sql);

echo $data[A1];

$sql="SELECT Column1 AS A1,Column2 AS A2,... FROM [Table-Name]
UNION
SELECT Column1 AS A3,Column2 AS A4,... FROM [Table-Name] ";


$data=mysql_fetch_array($sql);

echo $data[A1];