PHP代码链接oracle为什么会出错

1.$conn = oci_connect('username','password',"(DEscriptION=(ADDRESS=(PROTOCOL =TCP)(HOST=192.168.1.100)(PORT = 1521))(CONNECT_DATA =(SID=test)))");
2.$conn = oci_connect('username','password','192.168.1.100/test');

$sql = "select * from table_exmaple"
$ora_test = oci_parse($conn,$sql); //编译sql语句
oci_execute($ora_test,OCI_DEFAULT); //执行
while($r=oci_fetch_row($ora_test)) //取回结果
{
echo $ora_test[0];
echo "<BR>";
}

$dbconn = oci_connect('用户名','密码',"(DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=10.136.1.10)(PORT=1521))(CONNECT_DATA=(SID=pmsbp)))");