Question

I’m using MySQL to store financial stuff, and using the data to build, among other things, registers of all the transactions for each account. For performance reasons – and to keep the user from being overwhelmed by a gargantuan table – I paginate the results.

Now, as part of the register, I display a running balance for the account. So if I’m displaying 20 transactions per page, and I’m displaying the second page, I use the data as follows:

• Transactions 0 – 19: Ignore them – they’re more recent than the page being looked at.
• Transactions 20 – 39: Select everything from these – they’ll be displayed.
• Transactions 40 – ??: Sum the amounts from these so the running balance is accurate.

It’s that last one that’s annoying me. It’s easy to select the first 40 transactions using a LIMIT clause, but is there something comparable for everything but the first 40? Something like “LIMIT -40”?

I know I can do this with a COUNT and a little math, but the actual query is a bit ugly (multiple JOINs and GROUP BYs), so I’d rather issue it as few times as possible. And this seems useful enough to be included in SQL – and I just don’t know about it. Does anybody else?

Answer 1

The documentation says:

The LIMIT clause can be used to constrain the number of rows returned
by the SELECT statement. LIMIT takes one or two numeric arguments,
which must both be nonnegative integer constants, with these
exceptions:

• Within prepared statements, LIMIT parameters can be specified
  using ? placeholder markers.

• Within stored programs, LIMIT parameters can be specified using
  integer-valued routine parameters or local variables as of MySQL
  5.5.6.

With two arguments, the first argument specifies the offset of the
first row to return, and the second specifies the maximum number of
rows to return. The offset of the initial row is 0 (not 1):

SELECT * FROM tbl LIMIT 5,10;  # Retrieve rows 6-15

To retrieve all rows from a certain offset up to the end of the result
set, you can use some large number for the second parameter. This
statement retrieves all rows from the 96th row to the last:

SELECT * FROM tbl LIMIT 95,18446744073709551615;

Next time, please use the documentation as your first port of call.