sql - Using default constraint with null values? -


is there way insert default value if coming value null , constraint:

alter table student add constraint df_name default 'notavailable' [name]

when run this:

insert student (name,classid)values (null,1)

it still insert null instead of default value.

if understand you, want this:

insert student ( foo, bar, name ) values ( 'baz', 'qux', null )

to this:

insert student ( foo, bar, name ) values ( 'baz', 'qux', 'notavailable' )

(note think bad idea because null meant represent "notavailable" values - should avoid in-band values represent error conditions - , avoid string/text values represent status values)

(it's bad idea because checking "notavailabile" considerably more expensive checking null values - tables , indexes use more space , take longer seek , scan)

but if want this...

create trigger oninsertoverridenameifnull on student instead of insert      insert student ( foo, bar, name )     select foo, bar, isnull( [name], 'notavailable' ) [inserted]  end

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