mysql inner join error

[kath]

Hi

I am constructing an inner join with php - below is the code that my php code resolves to:

SELECT * FROM `comp-profile-01-general` a INNER JOIN `comp-profile-02-social` b ON `a.co_num` = `b.co_num` INNER JOIN `comp-profile-03-specialties` c ON `a.co_num` = `c.co_num` WHERE `a.co_num` = 300023

I am getting the error:
#1054 - Unknown column 'a.co_num' in 'where clause'

What have i done wrong?


Thanks.

[SpacePhoenix]

SELECT
    *
FROM 
    comp-profile-01-general AS a
INNER JOIN
    comp-profile-02-social AS b
        ON a.co_num = b.co_num
INNER JOIN
    comp-profile-03-specialties AS c
        ON a.co_num = c.co_num
WHERE a.co_num = 300023

When using an alias for a table the syntax is

table_name AS alias_name

Also do you need all fields from all three tables? If not just list the required fields only in the SELECT clause

[r937]

What have i done wrong?

you've put backticks around the tablename.columnname combo

so `a.co_num` is wrong, but `a`.`co_num` is right

a.co_num is also right, and it's "best practice" not to use backticks at all, based on naming your tables and columns so that there is no need to use backticks