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rdmershon/gist:819fa7f5a65c5905f99e808cc5bdd1d1

Created June 10, 2025 01:21
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SQL I can't remember, relationships between two tables pt.2
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gistfile1.txt
Foreign keys are used to establish relationships between tables. Typically, we use a primary key in one table and a foreign key in another table to create a one-to-one or a one-to-many relationship between those two tables.
In a one-to-one relationship, one table serves as a parent table and the other table serves as a child table. With a foreign key constraint, a record must exist in the parent table before a related record can be added to the child table. In other words, a record in the child table must have a related record in the parent table.
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rdmershon commented Jun 10, 2025

Foreign keys are referred to as FK when referring to the foreign key in the primary table. ex:

Employee
employee_id
name
email
department_id (FK)

Department
department_id
name

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