DBAs - Do you avoid collation errors?

You don't want this error:

When you write a stored proc - it must work regardless of the users collation. When you are joining to a temp table - meaning you are joining 2 different databases (eg. Northwind and TempDB) they won't always have the same collation.

The reality is that you can't tell a user what collation to run their TempDB - we can only specify the collation Northwind should be (we don't even want to specify that - we want that to be their default (as per their server)). Here is what you need to do:

SELECT
 #ClientSummary.ClientID,
 DateOfLastReminder = MAX(ClientDiary.DateCreated),
 DaysSinceLastReminder = DATEDIFF(day,MAX(ClientDiary.DateCreated),getdate())
 INTO #RecentReminderList
 FROM
 ClientDiary INNER JOIN #ClientSummary
 ON ClientDiary.ClientID = #ClientSummary.ClientID COLLATE
 database_default
 WHERE
 ClientDiary.CategoryID LIKE 'DEBT-%'
 GROUP BY
 #ClientSummary.ClientID