How to match not null + not empty?

问题

I have to do some queries on a messy database. Some columns are filled with either null or empty string. I can do query like this:

select * from a where b is not null and b <> '';

But is there a shortcut for this case? (match every "not empty" values) Something like:

select * from a where b is filled;

回答1:

Just:

where b <> ''

will do what you want as null <> '' is null and the row will not be returned

回答2:

select * from a where COALESCE(b, '') <> '';

来源：https://stackoverflow.com/questions/41938704/how-to-match-not-null-not-empty