Hi,
Thufir wrote:
SELECT product_name, customer.name, date_of_sale
FROM `sales` , product, customer
WHERE product.product_id = sales.product_id
and customer.customer_id = sales.customer_id LIMIT 0, 30
The above SQL command links three tables and display the required
result. The tables are linked by their ID fields.
<http://www.plus2net.com/sql_tutorial/sql_linking_table.php>
how is this different/better than a many-to-many, such as
<http://www.plus2net.com/sql_tutorial/sql_inner_join.php>? Isn't that
a better way of doing the same thing? Or, not?
I agree with the other respondent: they are the same thing. The comma-join syntax in
your first example is an "old-style" join, which used to be the only way to join
tables. The join using the JOIN keyword is equivalent, and I call it "ANSI-style" or
"new-style" or just "the right way."
I think whoever wrote the tutorial is using the words "linking table" a little
carelessly. Many RDBMS products have a notion of "linked tables" that is *totally*
different -- it has to do with accessing a table on one server from another server.
While it's true a JOIN, comma-style or not, does "link" data in one table to another
table, it is NOT a "SQL LINKING TABLE command" as implied in the tutorial. It is a
JOIN, and there is no such command as far as I know.
Baron
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