RSS
 

SQL wont return predefined values if table is empty

13 Oct

I have been working on a billing system in python-twisted for a while now. This system used scratch/serial to clear payments.
I had this callback that returns a Decimal.Decimal which is the value of the scratch card.

A little mod was required to allow direct API calls to clear payments, since the scratch/serial approach is still very much active, i figured it will be best to just refactor it all to work such that, if you pass in a scratch/serial, it checks on the database table, if a decimal e.g 1000.0  is passed in, then we have SELECT 1000.0 from scratch_pin_table;

We have 2 twisted servers running, a live and a test server.

everything works fine on the test server but failed on the live server.

Guess why, The test server has some entry in the scratch_pin_table while the Live has nothing because it has been truncated and scratch/pin has never been generated.

The result is

SELECT 1000.0 from scratch_lin_table returns 1000.0 as expected on test server but returns nothing on live.

Am i the only one or we are many who expects that selecting a predefined value in a query will return it even if table it empty?

it turns out that we are wrong.

you really cannot get anything from an empty table if you try that approach.

 
 

Leave a Reply