What Is Object Data Type in SQL?


Scott Campbell

What Is Object Data Type in SQL?

SQL (Structured Query Language) is a powerful programming language used for managing and manipulating relational databases. One of the key features of SQL is its ability to work with various data types, including object data types.

Understanding Object Data Types

An object data type in SQL allows you to store complex data structures within a database table. Unlike traditional data types such as integers or strings, object data types can contain multiple attributes and methods.

Object data types are particularly useful when you need to store and retrieve structured information that goes beyond simple values. They provide a convenient way to group related attributes together and encapsulate them within a single entity.

Creating Object Data Types

To create an object data type in SQL, you first need to define its structure using the CREATE TYPE statement. Let’s say we want to create an object data type called “Person” with attributes like “name,” “age,” and “address.” Here’s how you would define it:

  name VARCHAR2(50),
  age NUMBER,
  address VARCHAR2(100)

In this example, we defined a new object type called “Person” with three attributes: “name” (a string of maximum 50 characters), “age” (a numeric value), and “address” (a string of maximum 100 characters).

Using Object Data Types

Once you have created an object data type, you can use it as a column type when creating tables:

CREATE TABLE Employees (
  id NUMBER,
  employee_info Person

In this example, we created a table called “Employees” with two columns: “id” (a numeric value) and “employee_info” (of type “Person”). The “employee_info” column will store instances of the “Person” object type.

Manipulating Object Data Types

When working with object data types, you can perform various operations such as inserting, updating, and retrieving data. Here’s an example of how to insert a new row into the “Employees” table:

INSERT INTO Employees (id, employee_info)
VALUES (1, Person('John Doe', 30, '123 Main St'));

In this example, we inserted a new row with an ID of 1 and created a new instance of the “Person” object type with the name “John Doe,” age 30, and address “123 Main St.”

Retrieving Object Data Types

To retrieve data from a table that contains object data types, you can use the SELECT statement. Here’s an example:

SELECT employee_info.name, employee_info.age
FROM Employees;

This query will return the names and ages of all employees stored in the “Employees” table.


Object data types in SQL provide a flexible way to store and manipulate complex data structures within a database. By encapsulating related attributes together within an object type, you can organize your data more effectively and perform advanced operations on it. Whether you need to store information about employees, customers, or any other entities in your database, object data types can be a valuable tool.

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