多个查询条件的sql话语的拼写技巧,求指点

$where = array();<br />
foreach($_GET as $k=>v) $where[] = "$k like '%$v%'";<br />
$sql="select * from tb1";<br />
if($where) $sql .= ' where ' . join(' and ', $where);<br />

$sql="select * from tb1";<br />
$where = array();<br />
if($id=$_GET['id'])<br />
{<br />
    $where[]=" id like '%$id%'";<br />
}<br />
if($name=$_GET['name'])<br />
{<br />
    $where[]=" name like '%$name%'";<br />
}<br />
<br />
$s=(!empty($where)) ? " where " . implode(" and " , $where) : '';<br />
$sql.=$s;

<br />
$sql="select * from tb1 where 1=1";<br />
if($id=$_GET['id']) $sql.=" and id like "%$id%"";<br />
if($name=$_GET['name']) $sql.=" and name like "%$name%"";<br />