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History of 2019-08-26 PostgreSQL – COALESCE and NULLIF
2019-09-05
21:33 UTC
Revision 2
. . . .
Marcin Borkowski
–
+cat
(minor)
2019-08-26
20:42 UTC
Revision 1
. . . .
Marcin Borkowski
–
After the last week’s long post I decided that I needed some rest, so today I only have a short tip. It is a common need to say that we want the value of some variable x unless it is some kind of null value (depending on the language we use), in which case we want the value of some other variable y. The Lisp idiom for that is of course (or x y). In JavaScript, we usually say x || y, although this is risky if 0 is a valid value of x. (Hopefully, we will be able to say x ?? y in JS soon.) In my case, however, I needed this in SQL (more specifically, in PostgreSQL, but that doesn’t matter now).