Question

I inherited some code from a coworker and I noticed that the way that some of the code is not consistent
For example, is ther any functional difference between the following:

sum(case when (elephants = 0)then 1 else 0 end),

sum(case when (elephants = '0')then 1 else 0 end),

sum(case when (elephants IN (0))then 1 else 0 end),

sum(case when (elephants IN ('0'))then 1 else 0 end);

If there isn’t a functional difference between using single qutoes or IN vs = when looking for a single value, what other reason could account for it (other than sloppy code)?

Answer 1

x IN (a, b, c) means x = a OR x = b OR x = c. When the IN list contains a single item, x IN (a) just means x = a.

As for the difference between 0 and '0', the former is an integer, the latter is a character string. The latter can be converted to an integer, so when elephants is an integer too, elephants = 0 and elephants = '0' also test the same thing.

There is no real difference between the four.