How to count in a query in MySQL?

Anon

Hi,

If I want to make a query in a MySQL database, but I need only the number of results that meet the condition, how can I do that?

Another one: if I have two columns with timestamp data, and I want to know the average difference between the two in all records, what is the query then?

Thanks for your help.

Best wishes, Akos

Anon

Hey,

For the first one, I've at times used COUNT(*) or mysql_numrows() (or whatever based on the SQL you are using. With either, I assume that the query to the db is only going to ask for results that meet the conditions you refer to. If you just need the number of results, COUNT() is better. It is a one step process. Should be something like...

"SELECT COUNT(*) FROM someplace WHERE something = something"

Hope that helps (and is correct, I'm going from memory). By the way, it's in the MySQL manual that should've come with it. Check it there if you are still having issues.

later on,
Terrence

Anon

Thanks a lot. If I want to display the result on the screen, how can I refer to that?

Like $result=select count(*) from tb where cond=cond ;
and echo $result? Or something else?

Thanks, Akos

Anon

Hi Akos!

all the results are in an array, so you can use mysql_result(qiery,row,column) formula, for example in a for....

why dont you use limit? (if you want to limit the number of rows in a result set)? (or i may have misunderstood something... :o)

regards, (udv 🙂
tibyke

Anon

Hi,

You can't use $result like that to the best of my knowledge. Echoing $result back to the screen would prolly just show something like a result or resource ID. Instead, assign the output a variable and echo that back to the screen. Considering that this query should just returning just one result, the count, consider using mysql_result().

Later on,
Terrence