Good to know I’m not doing something stupid. Thanks. > On 30 Sep 2017, at 8:51 PM, Berend Tober <bto...@computer.org> wrote: > > Glen Huang wrote: > > I’m trying to make a column have these properties: > > > > 1. When a row is inserted, this column is allowed to be null. 2. When the > > row is updated, no null > > can be assigned to it this column. > > > > I initially thought I can drop the not null constraint before insertion and > > turn it back on after > > that, but after reading the doc it seems turning on not null constraint > > requires not columns > > contain null value, so looks like it won’t work. > > > > My current approach is to not set the not null constraint in the table and > > use a before update > > trigger to manually raise exception when the column is null. But it doesn’t > > seem as elegant. > > > > Is there a better way? > > > > Sounds to me like a BEFORE UPDATE trigger is exactly the way to handle this. > Rejecting invalid data input values is an ideal use case for such a facility.
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