Database Essentials - Predefined Functions - Overview of Functions

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Learn about the essential pre-defined functions in Postgres that can help you efficiently manipulate data. This article provides a comprehensive guide with explanations and code examples to get you started.

Explanation for the video:

The video linked in this article complements the text by visually demonstrating the concepts discussed. It provides a hands-on approach to understanding the usage of pre-defined functions in Postgres, making it easier for beginners to follow along.

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Key Concepts Explanation

String Manipulation

String manipulation functions allow you to manipulate and operate on strings efficiently. For example, the substring function extracts a substring from a given string.

SELECT substring('Thomas' FROM 2 FOR 3);

Date Manipulation

Date manipulation functions help you work with dates and times in Postgres. Functions like date_trunc or extract can extract specific parts of a date or time.

SELECT date_trunc('hour', current_timestamp);

Hands-On Tasks

Explore the following hands-on tasks to practice using pre-defined functions in Postgres:

  1. Use the substring function to extract a specific substring from a given string.
  2. Try using date manipulation functions to extract different components of a date.


In conclusion, we have covered the key concepts of pre-defined functions in Postgres, focusing on string manipulation and date manipulation functions. Practice these functions in your own queries and consider exploring further in the official Postgres documentation for a deeper understanding.

Overview of Pre-Defined Functions

Like any RDBMS, Postgres provides a robust set of pre-defined functions to help you solve business problems efficiently. The most common categories of functions include String Manipulation, Date Manipulation, Numeric Functions, Type Conversion Functions, CASE and WHEN, and more. For more detailed information, refer to the official documentation on the Postgres website.

Watch the video tutorial here