Question

i am new to sql joins.. i have project that is 5 year old . Now i have to deploy it some new server .so deploy it to other server there i am facing some sql problem. here is the qyery .

SELECT DISTINCT d.*,DATE_FORMAT(d.downloads_updated, '%c/%d/%Y') AS updated,DATE_FORMAT(d.downloads_created, '%c/%d/%Y') AS created, s2.strings_english as title, s2.strings_english as description 
FROM strings s, downloads d,
 products_has_downloads pd 
inner JOIN strings s2 ON d.downloads_description = s.strings_id WHERE d.downloads_id = pd.downloads_id AND s.strings_id = d.downloads_title AND d.downloads_status = 'Live' AND d.downloads_level = 'Public'
 ORDER BY d.downloads_updated DESC LIMIT 5

i am getting this error

1054 - Unknown column 'd.downloads_description' in 'on clause'

i have not written this sql query.it is working fine on old server .

I am new to join and database .please can any one help me .

Answer 1

You are mixing both implicit and explicit join syntax which will not work.

You have the following implicit syntax where the tables are joined by commas:

FROM strings s, downloads d, products_has_downloads pd 

The JOIN syntax has a higher precedence to the comma syntax so the alias for downloads is not available in the ON clause.

Try using all of the same syntax. I changed your query to use only explicit JOIN syntax:

SELECT DISTINCT d.*,
  DATE_FORMAT(d.downloads_updated, '%c/%d/%Y') AS updated,
  DATE_FORMAT(d.downloads_created, '%c/%d/%Y') AS created, 
s2.strings_english as title, 
s2.strings_english as description 
FROM strings s
INNER JOIN downloads d
  ON d.downloads_description = s.strings_id
INNER JOIN products_has_downloads pd 
  on d.downloads_id = pd.downloads_id
inner JOIN strings s2 
  on s2.strings_id = d.downloads_title
WHERE d.downloads_status = 'Live' 
  AND d.downloads_level = 'Public'
ORDER BY d.downloads_updated DESC 
LIMIT 5