SELECT seminar_name
FROM student_table GROUP BY seminar_name

SELECT DISTINCT seminar_name
FROM student_table

on this page on phpbuilder. (I had better luck with that "DISTINCT" version)

I'm *beginning* to get GROUP BY – but I don't see how your two examples are different…

If you had just:
SELECT date title FROM db
Each time you get a row (mysql_fetch_array) you can get the date and the title. (I'm assuming here it would be possible to have dates duplicated… more than one title per date)

In your example:
SELECT date, count(title) as count FROM db GROUP BY date
then each time you get a row, you can display the date and the count (number of titles for that date)

like:
11/20/2002 – count:2
11/21/2002 – count: 3

And here is where (I think) I get lost,
in your last example:
SELECT date, title, count(title) as count FROM db GROUP BY date
then each time you get a row you can display the date, and the count (number of titles for that date) AND(?) the title… so again, we're back to showing mulitple dates? so displaying the results could look like:

11/20/2002 – This is a title – count: 2
11/20/2002 – This is another title – count: 2

11/21/2002 – This is a new title – count: 3
11/21/2002 – This is yet a new title – count: 3
11/21/2002 – And our last title – count: 3

Is that correct?

As mentioned, in SQL "GROUP BY" is used to aggregate information. Several examples were mentioned. (I find COUNT, SUM, and MAX to be the most useful.) What was not mentioned is this:

If all variables other than those in the GROUP BY section are aggregated in the SELECT section, then everything works the way you think. If, however, you include other variables, then SQL creates the requested aggregate variables and then merges them back. An example will make this clearer.

If you have a database with date and title and did this:

SELECT date, count(title) as count
FROM db
GROUP BY date

you would get a list of dates with the number of titles for each date.

If you did this instead

SELECT date, title, count(title) as count
FROM db
GROUP BY date

you would, instead get your original table with a new column containing the daily count of titles. You could get the same result by running the first statement and then another which joined the result back to the original table (by date).

As far as the ORDER BY part: it simply takes the final output and sorts it.

What about the "Email this Entry" feature? Is that a standard MT feature?

Doing things that way will probably help you better understand both the order by and group by keywords. It's kind of difficult to visualize what is being returned by just putting the mysql statements into php and hoping for the best.

So in your sample query COUNT(source), and COUNT(category) would all return the total number of rows, i.e., the same number. That's not what you want. But in Lynda's query the COUNT() function is applied over the groups that are included in the GROUP BY clause, and that is what you want (I think).

GROUP BY just applies aggregate functions to the individual groups that are specified. That's its only reason for living.