What Is Foreign Key?

Foreign keys are the little guys that make your data easy to find. They're like the secret doorways to your data, except they're not isolated—they're right out in the open! Think of a foreign key as a cross-reference between tables. It links between one table's primary key and another table's primary key. That means it tells you where to look for data if needed! A foreign key is a group of columns in a relational database table that provides a link between data in two tables. It acts as a cross-reference between tables because it references the primary key of another table, thereby establishing a connection between them. A foreign key is typically used to ensure that it Can quickly join data and soon enter data for reporting and analysis purposes. When the values in one table are dependent on those in another table, then the value from one table should not be able to be inserted into the other table without causing an error. In database terminology, a foreign key is a field or set of domains in one table uniquely identifying the corresponding primary key in another table. The most common example of a foreign key in a database is a customer id in a purchase order. The customer id is a foreign key to the customer table's primary key. Foreign key A foreign key is a field in a table that points to a primary key in another table. It serves as a link between two different tables. By definition, a foreign key cannot exist independently; it must always be tied to a primary key elsewhere. This original table containing the primary key is known as the "parent" table or referenced table. The primary key can be referenced by multiple foreign keys from other tables, known as "child" tables.