SQL MAX of multiple columns?

📜 SQL MAX of multiple columns: Easy solutions for returning the most recent values 📊

So you've come across a problem where you need to return the maximum value from multiple columns in a SQL query. It seems tricky at first, but fear not! We have some easy solutions and examples to help you out. Let's dive right in!

The Challenge

Let's take a look at the context of the problem. You have a table called TableName with columns Number, Date1, Date2, Date3, and Cost. You want to return a result set that includes the Number, the most recent date among Date1, Date2, and Date3, and the corresponding Cost. How can you achieve this?

Solution 1: UNION and MAX

One way to solve this problem is by using the UNION and MAX functions. Here's an example query:

SELECT Number, MAX(Most_Recent_Date) as Most_Recent_Date, Cost
FROM (
    SELECT Number, Date1 as Most_Recent_Date, Cost FROM TableName
    UNION ALL
    SELECT Number, Date2 as Most_Recent_Date, Cost FROM TableName
    UNION ALL
    SELECT Number, Date3 as Most_Recent_Date, Cost FROM TableName
) as subquery
GROUP BY Number, Cost;

In this solution, we use a subquery to combine the columns Number, Date1, Date2, and Date3 using UNION ALL. Then, we use the MAX function to find the most recent date among all the columns.

Solution 2: CASE Statements

Another approach is to use CASE statements to determine the most recent date. Here's an example query:

SELECT Number,
    CASE
        WHEN Date1 >= Date2 AND Date1 >= Date3 THEN Date1
        WHEN Date2 >= Date1 AND Date2 >= Date3 THEN Date2
        ELSE Date3
    END as Most_Recent_Date,
    Cost
FROM TableName;

In this solution, we use CASE statements to compare the dates and select the maximum value. This approach is particularly useful if you have more columns to compare or a specific condition to consider when determining the most recent date.

Time to Level Up Your SQL Skills! ⚡️

Now that you have two solutions under your belt, it's time to put your newfound knowledge into practice. Experiment with these examples and adapt them to your specific SQL problem.

If you found this blog post helpful, let us know! Share it with your friends and colleagues who might also benefit from these easy solutions.

Got more SQL challenges? Leave a comment below, and our community of tech enthusiasts will be eager to help you out. Keep coding and keep learning! 💻

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