create table xtest01(col1 xmltype);
insert into xtest01 values ('<car><model>Audi TT</model></car>');
insert into xtest01 values ('<car model="BMW X5"/>');
select x.col1.extract('//car/model/text()').getstringval() from xtest01 x;
select x.col1.extract('//car/@model').getstringval() from xtest01 x; 
select * from xtest01 x where x.col1.existsnode('//car')  = 1;

working with XML (find out if element or attribute exists)

xml

PL/SQL