Re: Got a challenge for ya guys

On Mon, 25 Dec 2000, Noah Spitzer-Williams wrote: > aight i got these two tables: lets structure them like this: > > TABLE1 > > username | group | sex > john | 1 | M > mike | 1 | M > jen | 2 | F > > TABLE2 > > username | age > john | 2 > mike | 3 > jen | 2 > Just a minor point first. I am not sure how to create a field group? Isn't it a keyword? > here what i want to do: find how many unique groups are of age '2'? > > its quite easy to find how many different people are of age '2' but > how can i get the number of groups? select distinct t1.group from table1 t1, table2 t2 where t1.username = t2.username and t2.age = 2; > also, i dont want to list the same group more than once. i'd like to > have this all done in mysql so i can calculate how many results (see a > search engine comin here...hehe) Sometimes, you may have to use sub select queries if you want to develope more advanced queries along these lines, but as far as I know mysql doesn't support them. I use postgresql because of this reason. However, you can obtain the same results on mysql using multiple tables and queries. Anuradha