--- In ib-support@y..., "Paul Schmidt" <paul@t...> wrote:

>
> Dear List:
>
> I am using Firebird running on Linux Version (LI-T6.2.681 Firebird
> Release Candidate 2) .
>
> I have a set of dates in a table, and I want to split them up as 30.
> 60, 90 etc. I would have thought that
>
>
> SELECT FIELD1 FROM TABLE1 WHERE TABLE1.DATE >
> 'TODAY' - 30
>
> Would do it, but I get:
>
> ISC ERROR CODE:335544569
>
> ISC ERROR MESSAGE:
> Dynamic SQL Error
> expression evaluation not supported

Paul, I'm nit shure about new datatypes of dialect 3, but if Field1
is Timestamp it is strange. I use the same build and have a lot of
queries of this kind without any problem. Seems your problem is
relevant to tool, library or old gds32 you are using. Insert queries
like

Insert (TimestampField) into Table1 values ('today'-30)

returns exception "conversion error from string 'today'" but it is
solved by

Insert (TimestampField) into Table1 values (cast ('today' as
timestamp)-30)

Best regards, Alexander V.Nevsky