Why is this PostgreSQL not null constraint not catching this insert?
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24-02-2021 - |
سؤال
I have a table for users that includes two columns for contact information. A user can provide a phone number, an email, or both, but not neither.
I have the table set up with the following constraints
create table application_user(
-- other columns, primary key, etc.
phone text,
email text,
constraint valid_email check (((email IS NULL) AND (phone IS NOT NULL)) OR (email ~ '(?:[a-z0-9!#$%&''*+/=?^_`{|}~-]+(?:\.[a-z0-9!#$%&''*+/=?^_`{|}~-]+)*|"(?:[\x01-\x08\x0b\x0c\x0e-\x1f\x21\x23-\x5b\x5d-\x7f]|\\[\x01-\x09\x0b\x0c\x0e-\x7f])*")@(?:(?:[a-z0-9](?:[a-z0-9-]*[a-z0-9])?\.)+[a-z0-9](?:[a-z0-9-]*[a-z0-9])?|\[(?:(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.){3}(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?|[a-z0-9-]*[a-z0-9]:(?:[\x01-\x08\x0b\x0c\x0e-\x1f\x21-\x5a\x53-\x7f]|\\[\x01-\x09\x0b\x0c\x0e-\x7f])+)\])'::text)),
constraint valid_phone check (((phone IS NULL) AND (email IS NOT NULL)) OR (phone ~ '\d{10}'::text))
);
The idea is to make sure the email is valid if present and the phone is valid if present. However, when I run the following insert statement:
INSERT INTO application_user (email, phone) VALUES (null, null);
The insert still completes. What am I doing wrong here? I'm using PostgreSQL 12 if that matters.
المحلول
As the check constraint with the regex will only validate non-null values, I would split this up in three different check constraints:
create table application_user(
-- other columns, primary key, etc.
phone text,
email text,
constraint exactly_one check (num_nonnulls(phone, email)=1 ),
constraint valid_email check (email ~ '(?:[a-z0-9!#$%&''*+/=?^_`{|}~-]+(?:\.[a-z0-9!#$%&''*+/=?^_`{|}~-]+)*|"(?:[\x01-\x08\x0b\x0c\x0e-\x1f\x21\x23-\x5b\x5d-\x7f]|\\[\x01-\x09\x0b\x0c\x0e-\x7f])*")@(?:(?:[a-z0-9](?:[a-z0-9-]*[a-z0-9])?\.)+[a-z0-9](?:[a-z0-9-]*[a-z0-9])?|\[(?:(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.){3}(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?|[a-z0-9-]*[a-z0-9]:(?:[\x01-\x08\x0b\x0c\x0e-\x1f\x21-\x5a\x53-\x7f]|\\[\x01-\x09\x0b\x0c\x0e-\x7f])+)\])'::text),
constraint valid_phone check (phone ~ '\d{10}'::text)
);
check (num_nonnulls(phone, email)=1)
only validates that either one of the column is specified. The other two only check the format of the respective column. This - I think - makes things a bit easier to understand.
نصائح أخرى
Checking whether NULL
matches the pattern was not returning false
as I expected, it was itself returning NULL
, thus not violating the constraint. I was able to fix it by adding another NULL
check before the pattern match:
create table application_user(
-- other columns, primary key, etc.
phone text,
email text,
constraint valid_email check (((email IS NULL) AND (phone IS NOT NULL)) OR (email IS NOT NULL AND email ~ '(?:[a-z0-9!#$%&''*+/=?^_`{|}~-]+(?:\.[a-z0-9!#$%&''*+/=?^_`{|}~-]+)*|"(?:[\x01-\x08\x0b\x0c\x0e-\x1f\x21\x23-\x5b\x5d-\x7f]|\\[\x01-\x09\x0b\x0c\x0e-\x7f])*")@(?:(?:[a-z0-9](?:[a-z0-9-]*[a-z0-9])?\.)+[a-z0-9](?:[a-z0-9-]*[a-z0-9])?|\[(?:(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.){3}(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?|[a-z0-9-]*[a-z0-9]:(?:[\x01-\x08\x0b\x0c\x0e-\x1f\x21-\x5a\x53-\x7f]|\\[\x01-\x09\x0b\x0c\x0e-\x7f])+)\])'::text)),
constraint valid_phone check (((phone IS NULL) AND (email IS NOT NULL)) OR (phone IS NOT NULL AND phone ~ '\d{10}'::text))
);