Thank you for the answer.
I am looking at the source code H2 more specific Function.java
and I see that a couple of functions are initially set with Value.NULL
(since at that time the return data type is not known)
Although there is a method called optimize
that is used that for some functions the correct return data type is
calculated.
Could the same be done to the formula DATE_TRUNC in optimize?
Do you agree?
Our system connects to multiple database systems and depends a lot on the
data type being returned
(the SQL code is written by our users).
In my view, a NULL data type is a bit ambiguous for this cases comparing
with other systems with the same function date_trunc
like PostgreSQL that always returns the correct type.
Thank you for your time.
Pedro
On Thursday, 28 June 2018 14:31:39 UTC+1, Evgenij Ryazanov wrote:
>
> Hello.
>
> This function in H2 does not have exact return type, it may return
> TIMESTAMP, TIMESTAMP WITH TIME ZONE, DATE, or TIME depending on type of the
> second argument. That's why its return type is not defined. You can add an
> explicit cast.
> SELECT CAST(DATE_TRUNC('MONTH', column) AS TIMESTAMP)
> This construction looks ugly, but it should return an expected column type
> in meta data.
>
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