Скачать или смотреть How to Add Rows for Each Day Between Two Dates with SQL Server Using a Recursive CTE

Learn to effectively generate rows for each day within a date range in SQL Server using a `recursive CTE`. Ideal for managing large datasets!
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This video is based on the question https://stackoverflow.com/q/68294333/ asked by the user 'Cave Man' ( https://stackoverflow.com/u/16402993/ ) and on the answer https://stackoverflow.com/a/68294347/ provided by the user 'Gordon Linoff' ( https://stackoverflow.com/u/1144035/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Introduction

In the realm of data management, one common issue that database administrators and developers face is the need to create detailed records that reflect daily transactions or events. This is especially true when you want to generate entries for each day lying within a specific date range. Imagine having a table with order dates and shipping dates, and needing to create a new row for every single day in between those dates.

This problem is particularly challenging when dealing with large datasets that span across months. Manually coding individual rows would be extremely time-consuming and impractical. So, how can we automate this process in SQL Server?

In this guide, we will explore how to accomplish this using a recursive common table expression (CTE).

Understanding the Solution

What is a Recursive Common Table Expression?

A recursive CTE is a powerful SQL feature that allows you to perform iterative queries. This enables you to repeatedly execute a query until a certain condition is met. In our case, we will use it to generate new rows for each day in the specified range.

Sample Data Structure

Before diving into the solution, let’s look at our sample data. We have a table structured as follows:

NameDate of BirthOrder DateShipping DateJohn Smith02-24-200101-12-202101-15-2021M Jackson12-16-199203-17-202103-20-2021Our goal is to take the Order Date and Shipping Date for each person and generate a new row for every day in between, including the start and end dates.

The SQL Query

Here’s how you can achieve this with a recursive CTE:

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

Let’s break down this query further:

Breakdown of the Query

Common Table Expression Initialization:
The initial SELECT statement fetches all fields along with Order_Date as date_range.

Recursive Logic:
The second SELECT statement within the UNION ALL part calls the CTE itself. It adds one day to the date_range until it surpasses the Shipping_Date.

Date Range Condition:
The WHERE clause ensures that the recursion continues to generate rows until it hits the Shipping_Date.

Handling Recursion Limit:
The OPTION (MAXRECURSION 0) statement allows for recursion without a limit, which is essential for handling longer date ranges.

Conclusion

By using a recursive CTE, you can efficiently create rows for each day lying between an order date and a shipping date for your dataset within SQL Server. This technique saves you significant time and effort, especially when dealing with large datasets.

In summary, using SQL's recursive capabilities, managing date ranges can become a breeze and ensure you maintain accurate and full records without the headache of manual entries. So why not give it a try on your next project?

Happy querying!