Скачать или смотреть Solving the SUM of Multiple Columns in SQL Server

Learn how to effectively sum multiple columns across multiple rows in SQL Server. This guide explains how to tackle a common SQL problem with a practical example and solution.
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Understanding the Problem: Summing Multiple Columns in SQL

When working with databases, you may encounter situations where you need to compute totals by aggregating values across multiple rows. In this guide, we will tackle a specific problem related to SQL Server where we are required to sum multiple columns of data while also considering subtraction of values.

Consider the scenario represented by the sample table below:

IDValue1Value211033.900.0010.001033.9011181.600.00The goal here is to calculate a total for each ID, performing operations like 1033.90 - 1033.90 - 1181.60 which will give us the expected result of -1181.60.

The SQL Query Solution

To achieve this, the key is to use the SUM function in combination with a GROUP BY clause. Let's break down the steps needed to arrive at the solution.

Step 1: Setting Up the Table

Before we can execute our summation, we need to create a table and insert the necessary data. Below is the SQL code to do just that:

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

Step 2: Writing the SQL Command

Next, we can construct our SQL query. The query will sum the values in Value1 and subtract the values in Value2. Here is the SQL command you need:

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

Step 3: Understanding the Output

When you run the above command, SQL Server processes the data, grouping it by ID and calculating the total with the specified arithmetic operation. You will receive the following output:

IDTOT11181.60Additional Notes

It's important to note that if you only have one ID (as is the case in our example), the GROUP BY clause is technically unnecessary. However, it’s excellent practice to include it when working with more extensive datasets where multiple IDs are present.

Conclusion

In summary, summing multiple columns across rows in SQL Server can be efficiently managed using aggregation functions. By following the steps outlined above, you can easily compute the totals you need while accommodating both additions and subtractions.

With these strategies in hand, you are now better equipped to handle similar SQL queries in your own projects. Happy coding!