I'm not sure if this applies, but in my experience it is normal for a
unique value constraint to be satisfied on columns with null values,
as is a foreign key constraint, which is only evaluated on not-null
values. Following that precedent, I would say that the CHECK
constraint should pass if its expression results to null.
If you're trying to enforce a certain kind of behaviour in a
particular check constraint, you probably want to add some IS NULL
expressions to explicitly declare the behaviour you want, to specify
times when a null input would result in a check failure.
-- Darren Duncan
At 6:30 PM -0500 11/2/05, [EMAIL PROTECTED] wrote:
In a CHECK constraint, if the expression is NULL (neither true
nor false) does the constraint fail?
Example:
CREATE TABLE ex1(
x INTEGER,
y REAL,
CHECK( x<y )
);
Then you do:
INSERT INTO ex1 VALUES(5, NULL);
Does the check constraint fail or not? Or do different
database engines do different things?
I need to know so that I can make check constraint in SQLite
work like they do in other database engines...
