It’s a quiet month as we look forward to 2016, so I’m asking a series of survey questions for the next few posts.
My first one is about the order of join predicates.
When joining two or more tables in T-SQL, which do you prefer?
SELECT * FROM TableA a INNER JOIN TableB b ON a.Col1 = b.Col1
SELECT * FROM TableA a INNER JOIN TableB b ON b.Col1 = a.Col1
The SQL Server Query Optimizer doesn’t care, so it comes down to your preference.
For legibility, I prefer the first option, where the table order is reflected in the predicate order.
Some people like having the order reversed.
Which do you prefer, and why?