INNER JOINS: OLD, NEW, AND ALIASING v7.0
Perhaps the most common type of join is the inner join. An inner join 
is a join in which the values in the columns being joined are compared 
using a comparison operator.

In the SQL-92 standard, inner joins can be specified in either the FROM 
or WHERE clause. This is the only type of join that SQL-92 supports in 
the WHERE clause. These two types of joins have differing syntax.

The first and probably the most common is an inner join performed in 
the WHERE clause of a SQL statement and is termed the "old-style inner 
join".

SELECT Customer.Fname, Customer.LName, Orders.OrderNumber  
FROM Customer, Orders 
WHERE Customer.CustNumber = Orders.CustNumber

Alias the same statement to make it easier to read.

SELECT a.Fname, a.LName, b.OrderNumber 
FROM Customer a, Orders b 
WHERE a.CustNumber = b.CustNumber

The second and newer style of inner join is expressed as follows.

SELECT Customer.Fname, Customer.LName, Orders.OrderNumber 
FROM Customer INNER JOIN Orders ON Customer.CustNumber 
 = Orders.CustNumber

Alias the same statement to make it easier to read in conformance with 
the SQL-92 standard.

SELECT Customer.Fname, Customer.LName, Orders.OrderNumber  
FROM Customer AS a INNER JOIN Orders AS b ON a.CustNumber 
 = b.CustNumber

The syntax of these particular joins is said to be more intuitive as 
the join conditions are explicitly stated within the language of the 
SQL statement. Check out MSDN SQL Server Books Online for more 
information regarding these and other types of joins.
http://click.techrepublic.com/Click?q=3c-tK9RIcIo_bwZN2vQ00Qc8UnucdRR

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