> when we use generator,why do we use syntax like..
> if new.id=null
> new.id=gen(x,1)..why not just use 2nd line?

You can definitely use the second line only, but must people use this
statement in there BeforeInsertAndUpdate-trigger and therefor have to make
sure, the id does not get changed during updates.

> Also,I want to make sure that values in a column are unique..how can I
> do that beside using primary key(as another column is being used as
> primary key)and unique index(assuming only one uniques index is allowed
> per table)..

AFAIK you can have as many UINQUEs on a table as you want. But anyway: You
can make sure by using a before InsertUpdate-trigger checking for an
exists(select FIELD from table where FIELD=VALUE) on your FIELD and VALUE.

> Why does firebird does not have a boolean type?

It is not part of the standard.

> What is the difference between time and timestamp?

Someone else has to answer this one, I can't be exact enough in that
without looking at the manuals.

--
Thomas.Beckmann@...
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