Can table columns with a Foreign Key be NULL?

Can table columns with a Foreign Key be NULL?

sql mysql database foreign-keys

database

What's wrong with foreign keys?

database database-design foreign-keys referential-integrity data-integrity

database

The ALTER TABLE statement conflicted with the FOREIGN KEY constraint

sql sql-server database foreign-keys

database

Foreign key constraints: When to use ON UPDATE and ON DELETE

mysql sql database foreign-keys

database

Foreign Key naming scheme

database naming-conventions foreign-keys

database

Is it fine to have foreign key as primary key?

database foreign-keys primary-key

database

Are foreign keys really necessary in a database design?

database oracle foreign-keys

database

Adding a column as a foreign key gives ERROR column referenced in foreign key constraint does not exist

database postgresql foreign-keys alter-table

database

How to remove foreign key constraint in sql server?

sql-server database foreign-keys

database

MySQL InnoDB foreign key between different databases

mysql database foreign-keys innodb

database

MongoDB normalization, foreign key and joining

mongodb foreign-keys normalization database nosql

database

PostgreSQL: SQL script to get a list of all tables that have a particular column as foreign key

sql database postgresql foreign-keys

database

Meaning of "n:m" and "1:n" in database design

mysql database foreign-keys relationship

database

View all foreign key constraints for entire MySQL database

mysql foreign-keys database

database

Why are foreign keys more used in theory than in practice?

sql database foreign-keys

database