dates

Comparing ISO Week and US Week Numbers in SQL Server

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When working with dates in SQL Server, you’ll quickly find that there are different ways to calculate the “week number” of a given date. Two of the most relevant systems are the ISO week (ISO 8601 standard) and what we’ll call the US week numbering system. If you’re working in a US environment, the latter is often the default approach (due to your session’s language setting), while ISO weeks are the international standard. These different week numbering systems will often produce different results, which can be confusing if you don’t know why.

Let’s walk through the difference, and then we’ll test it with some simple examples.

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Building Readable Dates for Reporting Dashboards in SQL Server

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When you’re putting together reporting dashboards, raw datetime values like 2025-09-23 13:45:32.000 don’t do much for the average business user. People want to see “Sep 2025” or “Tuesday, September 23, 2025” rather than a timestamp that looks like it came straight from the database.

In many cases, formatting can also be handled in the reporting or application layer, which may be better for things like localization and display preferences. But there are plenty of situations where it makes sense to do this work in SQL Server itself. For example, maybe you need consistency or business-specific date logic. Fortunately, SQL Server gives us several tools for shaping dates into clear, readable labels that work well in dashboards.

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Handling International Date Formats When Casting to DATETIME in SQL Server

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Working with dates in SQL Server is usually quite straightforward. There’s a good range of date types and functions that we can use to manipulate date/time values.

But international date formats can undo all that simplicity in a heartbeat. Something as simple as casting a string into a DATETIME type can blow up depending on how the server interprets the input. This often happens when you’re dealing with applications or imports that don’t stick to a single culture or regional setting.

Let’s walk through an example and see why SQL Server behaves this way, and more importantly, how to handle it correctly.

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Get First and Last Day of Month in SQL Server for Reports

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When building reports in SQL Server, it’s common to filter or group data by month. A frequent requirement is to get the first and last day of a given month, often so you can build ranges for your WHERE clauses or generate summary tables. SQL Server gives us several ways to do this, and once you know the patterns, it’s quick to adapt for different reporting needs.

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Format Current Date as YYYYMMDD in SQL Server

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The ISO 8601 standard says dates should look like YYYY-MM-DD to avoid confusion between formats like MM/DD/YYYY or DD/MM/YYYY. But sometimes you might need to remove the hyphens and display the date as YYYYMMDD. Maybe your software doesn’t accept special characters, or you’re trying to save space. Whatever the case, here are some simple ways to get today’s date into YYYYMMDD format.

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A Quick Look at SQL Server’s DATETRUNC() Function

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SQL Server 2022 introduced the DATETRUNC() function, which makes working with date and time values much easier. It trims (or “truncates”) a date/time value down to a specified part (like year, month, or week) while setting all smaller units to their starting value. This helps avoid the common hack of mixing DATEADD() and DATEDIFF() just to snap a timestamp to the beginning of a period.

In this article we’ll look at some examples that demonstrate how it works.

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How to Add Days and Months to Dates in SQL Server

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When working with SQL Server, you may often find yourself having to shift a date by a certain number of days or months. While it sounds simple, the right function and approach can save you from subtle bugs and errors, especially when dealing with edge cases like leap years or month-end rollovers.

Let’s take a look at how to add days and months to dates in SQL Server.

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Troubleshooting Date Format Errors in SQL Server Imports

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Importing data into SQL Server is usually quite straightforward. That is, until you run into date and time formatting issues. Dates that look fine in a CSV, Excel, or flat file can suddenly throw errors or, worse, silently load with the wrong values. Since SQL Server is strict about how it interprets dates, mismatches between source file formats and SQL Server’s expectations are one of the most common headaches during imports.

This article looks at why these errors happen, what SQL Server expects, and how to troubleshoot these pesky date format issues.

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