Is it possible to set a default value in a SQL column to be consisted of other columns? For example, in the table below is it possible to have the EndDate default to StartDate + NoOfDays? So when inserting, I just need to do INSERT INTO xxx VALUES StartDate NoOfDays.
You can use a generated column:
create table mytable ( startdate datetime not null, noofdays int not null, enddate datetime as (startdate + interval noofdays day) );
You would then insert as follows:
insert into mytable (startdate, noofdays) values(now(), 3);
startdate | noofdays | enddate :------------------ | -------: | :------------------ 2020-12-12 01:28:27 | 3 | 2020-12-15 01:28:27
Note that this not exactly the same thing as default, which you mentioned in the question. A default applies to regular column, and is used only when no value is provided at
insert time. On the other hand, a generated column cannot be directly written to.
In SQL Server:
create table mytable ( startdate datetime not null, noofdays int not null, enddate as dateadd(day, noofdays, startdate) )