I have a SQL
select category, name, class, s_dt, f_dt from catgory
the class has three values:1, 2, 3
I hope the the s_dt and f_dt will be null even there is value in DB when calss =1
Then I hope s_dt and f_dt will be isnull(c.s_dt,'2000/01/01') s_dt, isnull(c.f_dt,'2078/12/31') f_dtwhen class = 2 or 3
How can I modify my SQL?