How Can I Group SQL Results by Month and Year in a Human-Readable Format?

Grouping SQL Results by Month and Year

When working with SQL databases, it often becomes necessary to group data by time periods, such as months or years. By default, SQL's GROUP BY clause groups rows based on individual months or years. However, you may encounter situations where you need to display the results in a more human-readable format, such as "month-year".

Problem: Displaying Month and Year in Grouped Results

Suppose you have a query that groups data by month and year and displays the results as follows:

SELECT MONTH(date) AS Mjesec, SUM(marketingExpense) AS SumaMarketing, SUM(revenue) AS SumaZarada 
FROM [Order]
WHERE (idCustomer = 1) AND (date BETWEEN '2001-11-3' AND '2011-11-3')
GROUP BY MONTH(date), YEAR(date)

This query will return results with the first column showing only the month, e.g., "9". The goal is to modify the query to display the month and year in a combined format, such as "9-2011".

Solution: Casting Date Values

To achieve this, you can use the CAST function to convert the month and year values into strings:

SELECT CAST(MONTH(date) AS VARCHAR(2)) + '-' + CAST(YEAR(date) AS VARCHAR(4)) AS Mjesec, ...

By casting the month and year values as strings, you can concatenate them into a single string that combines the month and year in the desired "month-year" format.

Alternative Solution: Leading Zeroes

If you require leading zeroes for the month value, you can use the following syntax:

GROUP BY 
  CAST(YEAR(date) AS VARCHAR(4)) + '-' + right('00' + CAST(MONTH(date) AS VARCHAR(2)), 2) 

This expression will ensure that all month values have leading zeroes, making the results more consistent and visually appealing.

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