Question

I have two tables and a foreign_key index table:
table xymply_locations
id
name
lat
lng

table xymply_categories
id
name

table xymply_categoryf_key
locid
catid

and i want to select the categories that are assigned to locid 1. How do I do this, I tried

SELECT * 
FROM `xymply_categoryf_key`, xymply_categories 
JOIN `xymply_categories` ON
        xymply_categories.id = xymply_categoryf_key.catid 
WHERE locid = 1; 

but I get "Not unique table/alias: 'xymply_categories' " and I’m wondering why…?

Answer 1

You’re mixing implicit (all tables listed in the FROM clause) and explicit JOIN styles in your code, hence the error.

SELECT xc.id, xc.name
    FROM xymply_categories xc
        INNER JOIN xymply_categoryf_key xck
            ON xc.id = xck.catid
    WHERE xck.locid = 1;