Can a foreign key reference the same table?
FOREIGN KEY constraints can reference another column in the same table, and is referred to as a self-reference. A FOREIGN KEY constraint specified at the column level can list only one reference column. This column must have the same data type as the column on which the constraint is defined.
Is Unique key same as foreign key?
By default, Unique key is a unique non-clustered index. Unique Constraint can not be related with another table’s as a Foreign Key. Unique Constraint doesn’t supports Auto Increment value.
How to add unique constraint as foreign key?
Add a unique constraint of a sql table as foreign key reference to an another sql table but still I have problem with this. First, you don’t need parentheses. Second, this is two constraints and you might as well give both names: Thanks for contributing an answer to Stack Overflow!
Which is the parent table in FOREIGN KEY constraint?
The vendor_groups table now is called the parent table that is the table to which the foreign key constraint references. The vendors table is called the child table that is the table to which the foreign key constraint is applied.
What is the referential integrity of a foreign key?
Table that defines primary/unique key and is referenced by foreign key is called primary table/master table/ Referenced Table. It is Defined in Create table/Alter table statement. For the table that contains Foreign key, it should match the primary key in referenced table for every row. This is called Referential Integrity.
How to create a foreign key in SQL Server?
To create a foreign key, you use the FOREIGN KEY constraint. The following statements drop the vendors table and recreate it with a FOREIGN KEY constraint: The vendor_groups table now is called the parent table that is the table to which the foreign key constraint references.