How to Create a Foreign Key on your tables.
This video will show how to create foreign key relationships between the parent and child tables.
I will show by example, how each of the constraint restrictions works, when the Update and Delete statements are executed: CASCADE, SET NULL, NO ACTION and SET DEFAULT.
So, a foreign key, sometimes abbreviated with FK, is a column or a combinations of several columns that enforce a constraint between two tables. This constraint promotes better data.
Parent table must have either a primary key on the needed column, or a unique index on that column.
Constraint on a SQL database
Referential integrity, foreign key, foreign keys, constraint, fk constraints, fk constraints explained, fk constraint errors,
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