Is a JOIN faster than a WHERE?

Question

Suppose I have two tables that are linked (one has a foreign key to the other):

CREATE TABLE Document (
  Id INT PRIMARY KEY,
  Name VARCHAR 255
)

CREATE TAB         


        

Answer 1

Explicit joins are easier to maintain as the intent of the query is much clearer. Also they are not subject to accidental cross joins so if you have a cross join in the query, the maintainer knows it was intended to be there.

If you ever need to use outer joins, you should know that the *= syntax is deprecated in SQL Server and will soon be removed. Also it currently doesn't function as expected all the time and may not give correct results and thus should NEVER be used. Mixing explicit outer joins and where clause joins (implicit joins) makes a query much harder for a maintainer to read and understand.