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Discover how to efficiently `combine multiple rows into one` using the STRING_AGG function in SQL Server. Learn the step-by-step process here!
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Combine All Rows into One: Using STRING_AGG in SQL Server

If you've ever found yourself needing to consolidate several rows of data into a single row in SQL Server, you're not alone. This is a common task, especially when dealing with reports or aggregating data for analysis. In this guide, we will explore how to achieve this effectively using the powerful STRING_AGG function available in SQL Server (version 2017 and later).

The Problem

Imagine you have a simple table that contains several rows of numerical data. For example, the following table contains numbers from 1 to 5:

NO12345Your goal is to combine these numbers into a single row that reads as 12345. This makes data easier to read and manipulate in some cases.

The Solution

Using STRING_AGG

For SQL Server versions 2017 and later, you can utilize the STRING_AGG function. This function is designed to concatenate values from multiple rows into a single string. Here’s how you can do it:

Create a Temporary Table: First, you'll need to declare a table and insert some sample values.

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

Use STRING_AGG to Combine Rows: After you've filled your temporary table with data, you can apply STRING_AGG to concatenate the numbers:

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

Explanation of the SQL Code

DECLARE Statement: This initializes a temp table @ TEMP to hold your values.

INSERT INTO: This command populates the temp table with integer values from 1 to 5.

SELECT STRING_AGG([NUMBER], ''): Here, we are combining the values from the NUMBER column into a single string. The second argument '' specifies that there should be no separator between the concatenated values.

Output

When you run the SQL code provided above, you will get a result as follows:

CombinedNumbers12345Conclusion

Utilizing STRING_AGG in SQL Server makes it simple to combine multiple rows into one, enhancing the presentation and usability of your data. Ensuring that you are using SQL Server version 2017 or later is crucial to leveraging this functionality.

If you often find yourself needing to aggregate row data into a single output, try out this method in your SQL queries! Happy coding!