SQL Where clause greater/less than multiple numeric columns

[#1]

I never thought I'd be asking an SQL question here. However today is the day!

Say I have a table with numeric columns A, B populated as follows. We can think of column A being a foreign key to a parent table, and column A and B together being the primary key of its child table:

A  B
1  1
1  2
2  1
2  2
3  1
3  2

I would like a SQL Select to return all records after, for example, (2, 1). I.e. (2, 2), (3, 1), and (3, 2).

Obviously the following won't work (it won't return (3, 1)):

select A, B from mytable when A > 2 and B > 1

I wish there were a way to write "A > 2 and B > 1" in a way that indicates B is "is a breakdown" of A, for lack of a better way to express it.

Of course I could create a derived column with the two numbers concatenated together, padded with enough zeros to accomodate maximum number size. Something like:

A  B  AandB
1  1  0101
1  2  0102
2  1  0201
2  2  0202
3  1  0301
3  2  0302

... Then I could write the SQL I want as:

select A, B from mytable when AandB > '0201'

However it would be wonderful if I could write a Where clause operating on the original numbers.

Maybe it would have been best to avoid multiple numeric columns making up a child table's key, although I'm not sure avoiding such would always eliminate the need for what I'm asking about.

This has been a tough one to Google search for solutions to. Thoughts and ideas are welcome!

[André_Schild]

If your know the number range of your columns, then perhaps just multiply the first one by for example 10000 and then filter n that one.

Something like:

select A, B from mytable where A*10000+B  > 20001

Of course only works if you don't run into a numeric overflow, and the array solution already mentioned is elegant. I'm just wondering how both solutions compare on the performance level for large tables

[dhkom]

Thanks. Great ideas from all!