You can do the calculation all in SQL. For example you can run a sub-select that queries the last value with something like 
(SELECT stock FROM yourtable ORDER BY timestamp DESC LIMIT 1) as last_
+value

[download]

and use that to compute the difference for inserting.

But the fact that such a simple thing looks rather complicated in SQL points into another direction: design smell. Storing both original data (the stock prices) and derived data (the difference) in the same table makes that rather hard.

Maybe there's a better way, like storing the derived data in view and let mysql update it automatically.

Perl 6 - links to (nearly) everything that is Perl 6.

In reply to Re: (OT) Dearest Monks - Mysql Question - Compare current insert record with last record inserted. by moritz
in thread (OT) Dearest Monks - Mysql Question - Compare current insert record with last record inserted. by jdlev

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