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GENERATE_SERIES Function New T-SQL Enhancements in SQL Server

In this article, we will explore the GENERATE_SERIES function in-depth, providing examples and use cases relevant to SQL developers, data engineers, and database administrators (DBAs). By the end of this article, you'll have a strong understanding of how to use GENERATE_SERIES effectively in various scenarios.

GENERATE_SERIES Function

The GENERATE_SERIES function in SQL Server 2022 generates a set of numbers or dates between a specified start and end value, with an optional step interval. This function is extremely useful in scenarios where a series of numbers or dates are required, such as generating a range of values for reporting, filling missing data points, or creating a temporary table for iteration.

Syntax

The function can be used to generate integer values, dates, and even time intervals, depending on the input type provided.

GENERATE_SERIES(start_value, stop_value [, step_value])

-- start_value: The beginning value of the series (required).
-- stop_value: The ending value of the series (required).
-- step_value: The increment between each successive value (optional).
-- If not specified, the default is 1.

Benefits

  • Simplicity: Simplifies the generation of sequences, replacing more complex approaches such as recursive Common Table Expressions (CTEs) or loops.
  • Performance: Optimized for performance, offering faster and more efficient series generation compared to traditional methods.
  • Flexibility: Allows for customizable step values, making it easy to generate both incremental and decremental sequences.

Use Cases
 

1. Generating a Series of Numbers

One of the most straightforward use cases for GENERATE_SERIES is to generate a sequence of numbers. Whether you need numbers for reporting, analysis, or data population, GENERATE_SERIES can help.

Example

SELECT value AS NumberSeries 
FROM GENERATE_SERIES(1, 10);
-- In this example, the function generates a series of numbers from 1 to 10.

SELECT value AS EvenNumbers 
FROM GENERATE_SERIES(2, 20, 2);
-- You can customize the step value to generate a sequence that increments by a specific value. 
-- For instance, to generate a series of even numbers.

Output

NumberSeries

2. Generating Test Data

When working in a development environment, generating large datasets for testing purposes is a common task. GENERATE_SERIES can help create mock data with minimal effort.

Example

SELECT value AS EmployeeID,
       'Employee' + CAST(value AS VARCHAR(10)) AS EmployeeName
FROM GENERATE_SERIES(1, 10);

Output

Result

3. Generating Date Ranges for Sales Reporting

Utilize the GENERATE_SERIES function to create a date range for sales reporting, filling in gaps for dates with no sales. This allows businesses to visualize daily sales trends and ensure comprehensive reporting, even on days with zero transactions, by aggregating sales data from related tables.

Example

USE AdventureWorks2022;
GO
WITH DateSeries AS (
    SELECT CAST(DATEADD(DAY, value, '2014-01-01') AS DATE) AS SaleDate
    FROM GENERATE_SERIES(0, 9)  -- Generates dates from '2014-01-01' to '2014-01-10'
)
SELECT ds.SaleDate, 
       COALESCE(SUM(d.UnitPrice * d.OrderQty), 0) AS SalesAmount
FROM DateSeries ds
LEFT JOIN Sales.SalesOrderHeader s 
    ON CAST(s.OrderDate AS DATE) = ds.SaleDate
LEFT JOIN Sales.SalesOrderDetail d 
    ON s.SalesOrderID = d.SalesOrderID
GROUP BY ds.SaleDate
ORDER BY ds.SaleDate;

Output

Dataservices

Performance Considerations

The GENERATE_SERIES function is optimized for performance, especially when compared to traditional methods like recursive CTEs or while loops. However, it’s important to be mindful of the following considerations:

  • Large Ranges: Generating large series with a very small step value can result in huge datasets. Be cautious when using GENERATE_SERIES with large ranges, as it may consume significant memory and CPU resources.
  • Indexes: If you're joining the generated series with large datasets, ensure that the joined columns are indexed for optimal performance.

Conclusion

The GENERATE_SERIES function in SQL Server 2022 is a powerful and versatile tool for SQL developers, data engineers, and DBAs. Its ability to simplify the generation of series, fill in missing data, paginate reports, and create test datasets makes it a must-have tool in any SQL toolkit. By replacing complex recursive queries or loops with GENERATE_SERIES, you can improve both the performance and readability of your code.

Whether you're generating number sequences, working with time series data, or creating dynamic reports, GENERATE_SERIES is a function that will save you time and effort. As SQL Server continues to evolve, features like GENERATE_SERIES will help developers and data professionals tackle common challenges with ease.


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