Question

I’m using MySQL and I have a table that has dates in a column (I’m making a table of due dates for a class). Previously I had the query as follows:

SELECT * FROM duedates_f2011 ORDER BY anothercolumn

In order to prevent duplicate occurrences (based on the duedate column) I had to change it as follows:

SELECT * FROM duedates_f2011 GROUP BY duedate

Currently, it’s retained the same order, but how can I assure that it will still do so? Nothing in the GROUP BY tutorials I’ve read indicates that it will still sort it, and adding an ORDER BY statement afterwards is incorrect. Is there something I’m missing, or is there something else I should add to make sure it remains in order?

(as indicated in my tags, I’m using PHP to run the query)

Answer 1

You can use group by ... order by ... (in this order). If you use just group by, it will be ordered automatically by that column(s).

However, if you want to group by duedate and order by anothercolumn, realize one thing: the sql doesn’t know which value to take for anothercolumn, when you group by duedate…

edit: from the mysql manual

If you use GROUP BY, output rows are sorted according to the GROUP BY
columns as if you had an ORDER BY for the same columns.