DDL: SQL Question Check Constraint on multiple columns

Question

create table Game(

isOn boolean,

playHour int,

isOff boolean,

constraint ck_isOn_hour check ( ? )

);

Constraint : playHour is NULL when isOn = FALSE

Replace the '?' symbol with a valid check for the given constraint.

Any help is much appreciated.

Answer 1

This should do it:

constraint ck_isOn_hour check (isOn or (playHour is null and not isOn))

This can be simplified:

constraint ck_isOn_hour check (isOn or playHour is NULL)