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Learn how to create an SQL query that effectively selects different columns for specified conditions. Perfect for structuring your database output precisely as needed!
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How to Write an SQL Query to Return Two Different Columns Based on Conditions

If you are working with a Microsoft SQL Server database, you may find yourself needing to extract data from a table based on specific conditions. One common scenario is when you want to display two different sets of information in separate columns from the same row based on certain criteria. This guide will guide you through how to write an SQL query that meets this requirement using a CASE expression.

The Problem

Imagine you have a database table structured to hold images associated with various locations. Each row in this table indicates whether an image is the main image or a logo image for a specific location. Here’s an example of what this table might look like:

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

In this scenario, our goal is to write an SQL query that returns the main image in one column and the corresponding logo image in another column.

Desired Output

From the table above, we want the output to look like this:

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

This structure allows for a clearer view of the main and logo images for each location by organizing them neatly into their respective columns.

The Solution: Using the CASE Expression

To achieve the required output format, we can utilize the CASE statement in T-SQL, which allows us to perform conditional logic directly within a SQL query. Here's how to do that:

SQL Query Structure

Below is the SQL query that performs the task of selecting the appropriate images based on their respective conditions:

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

Breakdown of the Query

SELECT with CASE: The query uses the SELECT keyword along with the CASE statement to determine which files belong in filename1 and filename2.

max(CASE WHEN [IsMainImage] = 'True' then filename end) retrieves the filenames marked as the main images.

max(CASE WHEN [IsLogo] = 'True' then filename end) retrieves the filenames marked as logos.

GROUP BY Clause: The GROUP BY location clause organizes the results by location. This way, for every unique location, we gather the main and logo images together.

Conclusion

Creating a conditional query to extract different columns for specified conditions can streamline how you view your database outputs. With the help of the CASE expression and the GROUP BY clause, you can easily customize what data is displayed in your query results.

Feel free to copy the SQL query provided and adapt it to your own tables and requirements. If you have further questions or additional scenarios, don’t hesitate to ask!