mySQL query

Peter B

I have a table which contains advertisments.

Each Advertisment has a model number and a date entered + other info.
I want to find the most recent 20 ads placed where the model numbers are unique.

Anyone know of a SQL query which will do the trick? (mysql)

TheFredJ

SELECT DISTINCT model_number FROM table ORDER BY DateAdded desc LIMIT 20

Peter B

That is what I thought, until I put it in practice.

I think the "distinct" deletes duplicate entries of model_number. And with only unique values orders by DateAdded.

Not sure exactly how "Distinct" works but I believe it makes a result table by going down through model_number values and entering all the entries into the result table which have a model number not previously entered. It ignores a row which has a model_number that has already been entered. Then it sorts it by the DateAdded.

It does not sort the most recent DateAdded with a particular model_number. It just sorts the order Distinct finds the unique model_number 's.

I hope this is clear

Peter B

Ah, think I have found it.

SELECT model_number, max(UNIX_TIMESTAMP(DateAdded)) as date1 FROM `ads` group by model_number order by date1 desc