Simple GROUP BY clause... error?

I am sure there is a simple reason why I am getting errors. I have used GROUP BY statements before and not had this problem. So there must be something small that is wrong with my syntax that I can't figure out (I'm currently going through the SQL cookbook trying to find out what I've done wrong!)

Here is my script:
SELECT a.plot_numbe, a.age_of_tre, a.sample_yea, a.species_co, a.total_heig, b.species_ty FROM
all_tree_2008 a
INNER JOIN a3a_species b on a.species_co=b.species_co
WHERE a.age_of_tre IS NOT NULL AND a.total_heig > 12 AND b.species_ty='S'
ORDER BY sample_yea, plot_numbe;

I would like to add in a 'GROUP BY a.plot_numbe' in there somewhere but no matter where I put it in the script I get an error. Things like "statement ended properly" or "not a GROUP BY expression".

Any ideas would be greatly appreciated!

Thanks in advance,

Ladygray

why you need GROUP BY? didn't see any reason to use GROUP BY clause.

1)GROUP BY clause normally used with aggregate functions such as SUM or AVG
2) Each non-aggregated field must be listed in the GROUP BY clause
3) GROUP BY should placed before ORDER BY

Hi Shamshe/ Rainbow River,

Thanks for your responses. I would like to group by plot number because the plot numbers are repeated because they are remeasured every five years. Shamshe, what did you mean by "non-aggregated field"?

Ladygray

suppose you have:
SELECT f1,f2,f3, SUM(f4)
FROM table1;
and you'd like GROUP BY then you have do:
SELECT f1, f2, f3, SUM(f4)
FROM table1
GROUP BY f1,f2,f3;

But there is no direct way to achieve what you want, need some trick. Give some time I'll get you some example how to do that.