表中有A B C三列,用SQL语句实现：当A列大于B列时选择A列否则选择B列，当B列大于C列时选择B列否则选择C列
declare
v_sal number:=2000;
v_tax number;
begin
case
when v_sal<1500 then
v_tax:=v_sal*0.03;
when v_sal<2500 then
v_tax:=v_sal*0.04;
when v_sal<3500 then
v_tax:=v_sal*0.05;
when v_sal< 8000 then
v_tax:=v_sal*0.08;
else
v_tax:=v_sal*0.1;
end case;
end;
/