Should I Normalize or Use a Junction Table to Store a List in a Database Column?

Storing a List in a Database Column: Normalization vs Junction Table

When faced with the need to store a list of objects within a database column, such as a list of fruits associated with a FOO object, the choice between normalization and a junction table arises.

Normalization prohibits the storage of a list in a single column. This approach creates a separate table for the list items, preserving data integrity and reducing redundancy.

However, in the case of our fruit list, this approach is not ideal. Fruit IDs are fixed and stored in another table. Normalization would require creating a new row in the fruit table for each fruit in the list, which would lead to data bloat and complexity.

A junction table, on the other hand, provides an alternative solution. It establishes a many-to-many relationship between the FOO object and the fruit list. Each row in the junction table represents the association between a specific FOO object and a specific fruit.

Here's an example of how a junction table can be implemented:

CREATE TABLE FOO (
  id int primary key not null,
  int1 int,
  int2 int,
  int3 int
)

CREATE TABLE Fruits (
  id int primary key not null,
  name varchar(30)
)

CREATE TABLE FOOFruits (
  FruitID int references Fruits (ID),
  FooID int references FOO(id),
  constraint pk_FooFruits primary key (FruitID, FooID)
)

To add the Apple fruit to the list of a FOO object with ID=5 using a junction table:

INSERT FOOFruits(FooID, FruitID)
SELECT 5, ID FROM Fruits WHERE name = 'Apple'

This approach eliminates the need for normalization and provides an efficient way to manage the relationship between FOO objects and fruit lists.

The above is the detailed content of Should I Normalize or Use a Junction Table to Store a List in a Database Column?. For more information, please follow other related articles on the PHP Chinese website!