In a relational database, what is a foreign key?A key used for encrypting dataA key used to unlock database tablesA key that points to a primary key in another tableA key used to sort data alphabetically

A foreign key in a relational database is a key that points to a primary key in another table. This is used to link two tables together. Here's a step-by-step explanation:

1. In a relational database, data is organized into one or more tables. Each table has a primary key, which uniquely identifies each record in the table.

2. A foreign key is a field (or collection of fields) in one table, that is used to link to the primary key in another table.

3. The table containing the foreign key is called the child table, and the table containing the primary key is called the referenced or parent table.

4. The foreign key in the child table will generally reference a primary key in the parent table. This means that the values in the foreign key column must match the values in a primary key column of the parent table.

5. This relationship allows us to cross-reference tables and combine data from multiple tables for querying and reporting.

6. It's important to note that a table can have multiple foreign keys depending on its relationships with other tables.

7. Foreign keys help to enforce referential integrity in the database. This means that the database remains consistent and accurate, and that the relationships between tables make sense.