I have the following code:

CODE
$mail_query = tep_db_query("select count(*) as count from " . visitors . " where receive = '1' ");
$mail_query = tep_db_query("select count(*) as count from " . TABLE_CUSTOMERS . " where customers_newsletter = '1' ");



But its only counting from the visitors table.

Why is this?

First off, is 'visitors' and 'TABLE_CUSTOMERS' defined constants? If the table name actually is 'visitors' it should be withing the string, as in

"select count(*) as count from visitors where receive = '1' "

If it is a variable you have forgotten the $, then it should be $visitors. The same thing goes for TABLE_CUSTOMERS. But since constants are normally made in upper case, I guess it actually is a constant(?).

Now to your question:

In your page, is the code written as it is above, with the two queries written next to each other? Cause you are storing the result in the same variable ($mail_query), so only the last one will be saved.

Is there any records in the TABLE_CUSTOMERS table? If there aren't any rows the count() will return zero. And are there any records with the field customers_newsletter set to '1'?

Finally, perhaps the most important question, are you getting any errors or warnings? If you are not, make sure you are not surpressing error messages. If there are still no errors the probelm probably lies in the database tables, perhaps there aren't any rows.

First off, is 'visitors' and 'TABLE_CUSTOMERS' defined constants? No

If the table name actually is 'visitors' it should be withing the string, as in
"select count(*) as count from visitors where receive = '1' "

Fixed

If it is a variable you have forgotten the $, then it should be $visitors. The same thing goes for TABLE_CUSTOMERS. But since constants are normally made in upper case, I guess it actually is a constant(?).

I have made the table to create a email only newsletter joining system and have not defined it anywhere within oscommerce.

Now to your question:

In your page, is the code written as it is above, with the two queries written next to each other? Cause you are storing the result in the same variable ($mail_query), so only the last one will be saved.

Ok I think thats were I am going wrong.

Is there any records in the TABLE_CUSTOMERS table? If there aren't any rows the count() will return zero. And are there any records with the field customers_newsletter set to '1'?

Yes I have set 1 in both tables so there are records.

Finally, perhaps the most important question, are you getting any errors or warnings?
If you are not, make sure you are not surpressing error messages. If there are still no errors the probelm probably lies in the database tables, perhaps there aren't any rows.
None