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Asked: 2024-09-26T17:47:09+05:30 In:

how to get monday from date in sql

I’m currently facing a challenge with my SQL queries and I could really use some help. I’m trying to figure out how to extract the Monday of the week from a given date. I understand that SQL has various date functions, but I’m not exactly sure which one I should use to achieve this.

Let’s say I have a date field in my table, and I want to create a new column that shows the Monday of that week for each date. I’m aware that weeks can start on different days depending on regional settings, but for this particular case, I want to standardize it to Monday.

I’ve tried a few different approaches, like using the `DATEPART` function to get the day of the week and then subtracting that from the date, but I’m not confident in my calculation. I’m worried I might be off by a day.

Is there a built-in function in SQL that can simplify this process? Or maybe a combination of date functions that would yield the result I need? Any clear examples or explanations would be greatly appreciated, as I’m hoping to streamline my reporting queries! Thank you!

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    2 Answers

    1. How to Get Monday from a Date in SQL

      So, you wanna figure out how to get Monday from a date in SQL? Okay, I’ll try to help you out! 😅

      First, let’s say you have a date, like '2021-10-21'. This date is a Thursday. If you wanna find the Monday of that week, you gotta do some math! 🧮

      In SQL, there’s this neat function called DATEADD and also DATEDIFF. I’m not super great with them yet, but here’s what I got:

      
SELECT DATEADD(DAY, -DATEPART(WEEKDAY, '2021-10-21') + 2, '2021-10-21') AS MondayDate;

      Okay, what’s happening here? 🤔

      • DATEPART(WEEKDAY, ...) gives you the number of the day in the week for your date. Like 1 for Sunday, 2 for Monday, etc.
      • Then you subtract that number from 2 (because we want Monday, which is 2).
      • Finally, you use DATEADD to subtract that many days from your original date.

      So running that query should give you the Monday of that week. 🎉

      Just imagine if your date was a different day; you’d get Monday from that week, which is pretty cool!

      Hope this helps, even if it’s super basic! Good luck with SQL, it gets easier, I promise! 🚀


    2. To retrieve the Monday of the week for a given date in SQL, you can utilize a combination of the `DATEADD` and `DATEDIFF` functions to calculate the offset from the given date. The approach involves determining the day of the week for the input date and then subtracting the appropriate number of days to get back to Monday. For SQL Server, the calculation can be done using the following query:

      “`sql
      SELECT DATEADD(DAY, 1 – DATEPART(WEEKDAY, @YourDate), @YourDate) AS MondayOfWeek
      “`

      In this query, `@YourDate` is your input date parameter. The `DATEPART(WEEKDAY, @YourDate)` function returns an integer representing the day of the week, where Sunday is typically considered as the first day (1). Thus, by subtracting this value from 1 and using `DATEADD`, you can effectively roll back to the previous Monday. If you are using MySQL, you can achieve the same result via:

      “`sql
      SELECT DATE_SUB(@YourDate, INTERVAL WEEKDAY(@YourDate) DAY) AS MondayOfWeek;
      “`

      Here, `WEEKDAY(@YourDate)` yields an integer from 0 (Monday) to 6 (Sunday), and `DATE_SUB` allows you to subtract the number of days accordingly to obtain the Monday of that week.

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