On Thu, Oct 13, 2022 at 02:28:23PM +0000, PG Doc comments form wrote: > The following documentation comment has been logged on the website: > > Page: https://www.postgresql.org/docs/15/functions-conditional.html > Description: > > Regarding: > https://www.postgresql.org/docs/current/functions-conditional.html > > I ran into a situation where COALESCE was used like this > > ``` > SELECT * FROM table WHERE COALESCE(col_1, col_2, col_3) >= 5 > ``` > > and didn't understand how it worked, and the examples don't really help > because they only use COALESCE like > > ``` > SELECT COALESCE(..) > ``` > > I asked and answered a question on stackoverflow with a pretty good example > of this, you could consider adding to your page. > > Thank you :)) > > Stackoverflow question link: > https://stackoverflow.com/questions/74057319/coalesce-in-postgresql-conditional-displaying-seemingly-undocumented-behavior
I read the Stackoverflow thread and it seems you thought a column name in the function in a WHERE clause should span all the rows looking for the first non-NULL row, and only if they are all NULL, go to th next parameter. All WHERE functions are row-based so I don't see how to actually improve our doc text without making it more confusing. Sorry. -- Bruce Momjian <br...@momjian.us> https://momjian.us EDB https://enterprisedb.com Indecision is a decision. Inaction is an action. Mark Batterson
