Скачать или смотреть Efficiently Generate N Records in PostgreSQL with Ease: Harnessing the Power of generate_series

Discover how to use PostgreSQL's `generate_series` function to efficiently create multiple records, and add relations effortlessly.
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This video is based on the question https://stackoverflow.com/q/70164726/ asked by the user 'Dex' ( https://stackoverflow.com/u/148390/ ) and on the answer https://stackoverflow.com/a/70164757/ provided by the user 'Tim Biegeleisen' ( https://stackoverflow.com/u/1863229/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Streamlining Data Insertion in PostgreSQL

When working with databases, particularly in PostgreSQL, developers often encounter the need to insert multiple records quickly. Whether you’re populating a test environment or preparing for production, manually entering data can be tedious and error-prone. Fortunately, PostgreSQL offers tools like generate_series that can significantly streamline the process of inserting records.

The Challenge

Let’s say you want to insert multiple user emails into a users table and subsequently establish relations for their respective profiles. A typical manual approach might look something like this:

[[See Video to Reveal this Text or Code Snippet]]

Following the insertion of users, you might write separate INSERT statements for their profiles, like so:

[[See Video to Reveal this Text or Code Snippet]]

While this method works, it’s not efficient, especially for inserting a large number of records.

The Solution: Using generate_series

Step 1: Inserting User Emails

Instead of manually crafting each insert statement, you can leverage the generate_series function to create the necessary email addresses on-the-fly. Below is how you can insert three users into the users table efficiently:

[[See Video to Reveal this Text or Code Snippet]]

Explanation:

WITH cte AS (...) creates a Common Table Expression (CTE) that generates a series of integers from 1 to 3.

The INSERT INTO command concatenates these integers to form email addresses and inserts them all at once.

Customization Tip:

If you need to generate more than three user emails, simply adjust the second parameter in the generate_series function. For example, to create 10 emails, replace 3 with 10.

Step 2: Inserting User Profiles

Once the users are inserted, the next step is to link them to their profiles based on the emails. With the help of another generate_series, this can also be accomplished efficiently:

[[See Video to Reveal this Text or Code Snippet]]

Explanation:

This CTE generates a list of email addresses just as done previously.

The INSERT INTO profiles command then selects all user IDs from the users table that match the newly created emails and inserts them into the profiles table.

Conclusion

Using the generate_series function in PostgreSQL not only simplifies the process of inserting multiple records but also reduces the risk of human error. It allows you to generate dynamic data efficiently, making it an invaluable tool for developers working with databases.

Whether you're working on a development project, importing test data, or dealing with production data, mastering generate_series can save you significant time and effort. So next time you find yourself manually inserting records, consider utilizing this powerful feature to automate and streamline your workflow.