Author: Tomas Rutkauskas 

Decrementing a datetime field in Paradox

Answer:

There is a bug in Local SQL on Paradox:

Executing an Update statement on a Paradox table where '1' is being subtracted in a 
datetime field does not subtract '1', but rather adds '1'.
1   
2   // this will ADD one!
3   UPDATE SAMPLE.DB set DT = DT - 1
4   
5   // the following workaround will give the correct result:
6   UPDATE SAMPLE.DB set DT = DT + (-1)