In this lesson, we will look at how to update a database, i.e., edit the values of existing fields in the table.
The rows represent instances of that type of entity (such as "Lee" or "chair") and the columns representing values attributed to that instance (such as address or price). Rows in a table can be linked to rows in other tables by adding a column for the unique key of the linked row (such columns are known as foreign keys).
Most relational database designs resolve many-to-many relationships by creating an additional table that contains the PKs from both of the other entity tables—the relationship becomes an entity; the resolution table is then named appropriately and the two FKs are combined to form a PK.
The migration of PKs to other tables is the second major reason why system-assigned integers are used normally as PKs; there's seldom efficiency nor clarity in migrating a bunch of other types of columns.
of the programming within a RDBMS is accomplished using stored procedures (SPs).
Often procedures can be used to greatly reduce the amount of information transferred within and outside of a system.Codd showed that data relationships of arbitrary complexity can be represented by a simple set of concepts.