question about "group by" sql select statement

[windskystar73]

I have a table, called "person" that has "name" and "id" column that has the following data.

id, name
1 Tom
2 David
1 Tom
3 John
2 David

I want to display duplicated rows. i tried like this.
select * from person having count(*) > 1;
but it displays only one row.
but this statement returns what I want.
select * from person group by id, name having count(*) > 1;

can anybody tell me the difference between these two select statements?

thanks..

 

[swampBoogie]

When using having without a group by you will get one group consisting of the complete table (as there is no where clause).

Try the query

select count(*) from person having count(*) > 1

which should give the result 5.

select * from person having count(*) > 1

should give an error.