Database Essentials using Postgres - Creating Tables and Indexes - Overview of Sequences

Databases Postgres
1

Description:
This article provides a comprehensive guide on working with sequences in PostgreSQL. It covers key concepts, step-by-step instructions, hands-on tasks, and practical examples to help readers understand and utilize sequences effectively.

Explanation for the video:

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Key Concepts Explanation

Surrogate Primary Keys

Surrogate primary keys are unique identifiers used in relational databases. In PostgreSQL, these can be implemented using the SERIAL keyword. Example:

CREATE TABLE users (
    user_id SERIAL PRIMARY KEY,
    ...
)

Sequences

Sequences in PostgreSQL are used to generate numerical values for surrogate primary keys. They can be defined with properties like START WITH, INCREMENT BY, MINVALUE, MAXVALUE, etc. Example:

CREATE SEQUENCE test_seq
START WITH 101
MINVALUE 101
MAXVALUE 1000
INCREMENT BY 100

Hands-On Tasks

  1. Create a sequence test_seq starting with 101 and incrementing by 100.
  2. Use the sequence to populate a table users with surrogate primary keys.
  3. Insert records into the users table using the sequence-generated keys.

Conclusion

In this article, we explored the usage of sequences in PostgreSQL for generating surrogate primary keys. By following the hands-on tasks and examples provided, readers can effectively implement sequences in their database schemas and improve data management.

Overview of Sequences

  • Define primary key constraints for tables in relational databases.
  • Utilize SERIAL in PostgreSQL to create surrogate primary keys.
  • Use sequences to support surrogate primary keys and ensure uniqueness.
  • Maintain sequence properties like START WITH, INCREMENT BY, MINVALUE, MAXVALUE.
  • Interact with sequences using functions like nextval and currval for generating and retrieving sequence numbers.
  • Reset sequences with RESTART WITH after populating tables with surrogate key values.

Watch the video tutorial here