You don't.

First you decide on the desired PK. Then you address any dupes. Then you issue an ALTER to set the PK.

No, I only want to make it in OneQuery.

Remember, i only used this first query to get the list of what was changed during a period from a user...

So do you want two queries? One showing the situation before mess-up (which is the one already provided) and one showing the mess-up? That is, two separate resultsets?

Phil, I am sorry, I spoke too quickly.

I see that you DECLARE a fixed time DECLARE @MessedUpAt DATETIME = '2000-01-03 15:00:00';

But the mechanic can mess up for 2 hours.......

Thanks Phil, you did it! Please do you mind, explain high level how this works? You probably see that I do not have your level and I am interested...

Please check this out and let me know what you think. I used a temp table and converted your VARCHAR(1) to CHAR(1). If you want to know why VARCHAR(1) is...

I need a bit of clarification.

Presumably the inputs to this query would be

a) Mechanic (Mike, in your example), and

b) MessedUpAt (2000-01-03  at 15:00:00, in your example)

Is this correct?

Based on these...

Someone got...

Nice. Well done on posting...

I seem to recall a rule in place that if 3 posts for the same user are flagged as spam, the user automatically gets disabled.  Is that rule still...

I've been called many things, but it's a first for Ohil 🙂

The people that make spam aren't stupid, the spam constantly evolves as they find new ways to avoid in built spam detection on websites; no doubt this is just...

I fragged a load of them earlier. We've been down this road several times before, with many suggestions which sounded like great ideas, though none seem to have ever been...

Like this? (With thanks to Jeff Moden for the dates generator.)

DROP TABLE IF EXISTS #t1;

CREATE TABLE #t1
(
    PersonId INT NOT NULL
   ,StartDate...

To convert NVARCHAR to decimal, use something like this:

SELECT Cost = CAST(t1.Cost as Decimal(19,6))

Use AVG() to calculate averages.

For more-specific help, please post the sample data in consumable format, along with...