Question

I was helped out with this select query that I am using to get all tables with null values in two columns

select count(*)
from (
   select LastModifiedDate from Table1
      union all
   select LastModifiedDate from Table2
      union all
   select LastModifiedDate from Table3
) a 
where LastModifiedDate is null

To update all three tables is there a better way to do it then

Update table1
SET LastModifiedDate = GETDATE()
WHERE LastModifiedDate is null

Update table2
SET LastModifiedDate = GETDATE()
WHERE LastModifiedDate is null

and so on?
Sorry I split the query’s one looks for CreationDate and one looks for LastModifiedDate

Answer 1

Yes, there is a better way. As Gordon Linoff noted in the comments, you might overwrite valid created dates with your proposed query.

Try this instead:

Update table1
SET CreationDate = ISNULL(CreationDate,GETDATE())
  , LastModifiedDate = GETDATE()
WHERE CreationDate is null or LastModifiedDate is null

Update table2
SET CreationDate = ISNULL(CreationDate,GETDATE())
  , LastModifiedDate = GETDATE()
WHERE CreationDate is null or LastModifiedDate is null

Update table3
SET CreationDate = ISNULL(CreationDate,GETDATE())
  , LastModifiedDate = GETDATE()
WHERE CreationDate is null or LastModifiedDate is null

Using ISNULL will preserve existing CreationDate data. You don’t want to use it for LastModifiedDate, because you’re going to be modifying the rows, so that value should change.

However, there’s no reason to try and restructure your statements, as there’s nothing wrong with them.