UPDATE met zelf lid worden
SQL Fiddle http://www.sqlfiddle.com/#!2/b4f6c/1
UPDATE Table1 T1
JOIN Table1 T2
on T1.id=T2.id+1
SET T1.col2 =T2.col2 ;
UPDATE Table1 set col2 =NULL
Where id=1;
EDIT:In enkele verklaring
UPDATE Table1 T1
LEFT JOIN Table1 T2
on T1.id=T2.id+1
SET T1.col2 =T2.col2 ;