Question

There is one table which is having only one row with 4 date columns ,initially all date value are null so

if Exists(select 1 from rep_master where pacdt_1=null OR
pacdt_2=null OR
pacdt_3=null OR
pacdt_4=null)
select 0
else
select 1

this one is returning 1

if Exists(select 1 from rep_master where ISNULL(pacdt_1,0)=0 or
ISNULL(pacdt_2,0)=0  or
ISNULL(pacdt_3,0)=0 or
ISNULL(pacdt_4,0)=0 )
select 0
else
select 1

this one is returning 0 ,which is correct result
I m unable to figure out what is wrong with first query?

Answer 1

use IS NULL rather than = NULL

so:

if Exists(select 1 from rep_master 
          where pacdt_1 is null OR pacdt_2 is null OR
                pacdt_3 is null OR pacdt_4 is null)
   select 0
else
   select 1