how to handle null in date field of postgresql

Question

I have to ignore rows which have null in date column. How can I do it?

select s."SR Closed Date"::date,
       s."Service Request Number",
       a."Activity ID" 
from sr_data_master s,
     activity_master a
where s."Service Request Number" = a."Service Request Number"
and a."Service Request Number" is not null 
and a."Service Tag" is not null 
and a."Activity ID" is not null
and s."SR Closed Date"::date is not NULL
group by s."Service Request Number",
         s."SR Closed Date"::date,
         a."Activity ID";

I am getting the error:

 invalid input syntax for type date: "NULL" 

Answer 1

The error message indicates that your "date" column (which apparently isn't actually a date column) contains the string constant 'NULL' rather than a real null value (because there is no problem casting a real null value to date value).

You could use the following condition to exclude those rows:

and s."SR Closed Date" <> 'NULL'

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But the correct fix for this problem is to store date values in DATE columns. Then you don't need the casting and you can't store invalid date values to begin with.