Hello,

Im new with database and I have a question about a table with triggers or maybe a check constraint. Im using SQL Server Management studio.

I have the following create tables:

create table bid(
seller char(10) not null,
item_nummer numeric(3) not null,
)

create table Item(
startprice char(5) not null,
description char(22) not null,
start_date char(10) not null,
end_date char(10) not null,
seller char(10) not null,
item_nummer numeric(3) not null,
)

What i'm trying to make is this trigger/constraint:
colomn "seller" from table Item will get NULL as long as systemdate is > start_date and end_date, then it will get the value from seller from table bid on the same item_nummer in both table).

I hope i explained correctly what i mean.