In PostgreSQL, user-defined data types allow developers to create custom data structures tailored to specific application needs. This feature enhances the database's flexibility and efficiency by allowing complex data types to be stored and manipulated directly.

Creating a User-Defined Type:

To create a user-defined type in PostgreSQL, you use the CREATE TYPE command. This command allows you to define a composite type, which is a structure containing multiple fields.

Example: Creating a Composite Type:

Let's create a composite type for storing address information:


CREATE TYPE address AS (
    street VARCHAR(50),
    city VARCHAR(50),
    state CHAR(2),
    zip_code CHAR(5)
);

Using the Custom Type:

Once created, you can use the custom type in table definitions, functions, and more. Here is an example of using the address type in a table:


CREATE TABLE customers (
    customer_id SERIAL PRIMARY KEY,
    name VARCHAR(100),
    address_info address
);

Benefits of User-Defined Types:

User-defined types provide several benefits, including improved data integrity, easier maintenance, and the ability to encapsulate complex data structures within the database.

Considerations:

While user-defined types offer flexibility, they can also add complexity to your database schema. It's important to carefully plan their use to ensure they meet your application's requirements without complicating data management.

Console Output:

Type and table created successfully.