Скачать или смотреть How to SUM UP Two Columns and Find the MAX Value in SQL Server

Discover an easy way to sum two columns and retrieve the maximum value in SQL Server. Follow our step-by-step guide and solve your database queries effectively!
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Understanding How to Sum Two Columns and Find the Maximum Value in SQL Server

When working with databases, you may often need to analyze data in various ways. One common task is summing values from multiple columns and finding the maximum result. If you're using Microsoft SQL Server and encountered this challenge, you're not alone.

In this guide, we'll explore how to effectively sum two columns, handle potential NULL values, and retrieve the row with the maximum sum from SQL Server.

Let’s break it down step-by-step!

The Problem

Imagine you have a table named table1 that contains employee data as shown below:

E_IDE_NameT1T21Alice55502Morgan60403John654Monica30105Jessica256Smith205You want to find the E_ID and E_Name of the employee whose sum of T1 and T2 is the highest. However, when trying to write your SQL query, you encounter an error regarding the aggregation methods. This can be a common issue when you're working with SQL queries where not all selected fields are included in an aggregate function.

The Solution

Step 1: Summing the Columns

First, we will create a subquery that computes the total by summing T1 and T2. We will use the ISNULL function to handle any NULL values effectively:

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

Step 2: Retrieving the Maximum Value

Now, you’ll want to order this result by the total in descending order and select the top result. Here’s how you can do this:

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

Explanation of the SQL Query

Subquery:

We create a derived table Q1 that contains E_ID, E_Name, and the calculated Total from summing T1 and T2.

The ISNULL function ensures that if T2 has a NULL value, it will be treated as 0.

TOP Clause:

The TOP (1) clause limits the result set to only one row—the row with the highest total.

ORDER BY:

We sort the results by Total in descending order. This ensures the maximum total appears first.

Conclusion

By following these steps, you can easily sum two columns in SQL Server and retrieve the employee data with the highest total. This method not only handles potential NULL values efficiently but also keeps your code clean and readable.

If you run into any issues or have more questions about SQL queries, feel free to ask in the comments below!