pinkfloydhomer@gmail.com wrote:
> What's the difference between:
>
> SELECT accountno, name
> FROM accounts, customers
> WHERE accounts.customerno = custommers.customerno;
>
> and
>
> SELECT accountno, name
> FROM accounts INNER JOIN customers
> ON accounts.customerno = custommers.customerno;
>
> ?
>
> Are there any theoretical differences? Any practical differences?
>
> /David

The second one is easier to change to say a left join. Also, when you add
more than one join, the second one is far clearer to read.

Also, as I'm sure you read in the manual, "However, the precedence of the
comma operator is less than of INNER JOIN, CROSS JOIN, LEFT JOIN, and so on.
If you mix comma joins with the other join types when there is a join
condition, an error of the form Unknown column 'col_name' in 'on clause' may
occur. Information about dealing with this problem is given later in this
section."

http://dev.mysql.com/doc/refman/5.0/en/join.html