Hi,

Can someone explain me what is the rule in using single or double
quotes?

It seems that double quote works if you use it in a field or table
name but doesn't work in where clause for values. And the Single
quote is the opposite.

I'm just curious if this is done on purpose for SQL compliance or just
a current limitation.

I came across this problem when converted some old simple SQLS that
worked in Oracle (which supports just about everything including
apples and bananas) and now doesn't work in Firebird.

It's not really a request, but more for learning purpose and personal
documentation. I don't want Firebird to be a monster like Oracle, I
like its simplicity.