Tag: dates

DATEDIFF() vs DATEDIFF_BIG() in SQL Server: What’s the Difference?

Posted on by Ian

If you’ve ever needed to find the difference between two dates in SQL Server, you might have used the DATEDIFF() function. This function returns the amount of time between two dates using a datepart specified by you. For example, you could use it to return the number of days between date 1 and date 2. You can also get it to return the number of minutes, seconds, months, years, etc.

The DATEDIFF_BIG() function works exactly the same way, but with one subtle difference: Its return data type.

So the difference between these two functions is the data type of their return value.

  • DATEDIFF() returns a signed integer (int)
  • DATEDIFF_BIG() returns a signed big integer (bigint)

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What is the Year 2038 Problem?

Posted on by Ian

The Year 2038 problem (also referred to as the Y2K38 bug) refers to a problem that some computer systems might encounter when dealing with times past 2038-01-19 03:14:07.

Many computer systems, such as Unix and Unix-based systems, don’t calculate time using the Gregorian calendar. They calculate time as the number of seconds since 1 January 1970. Therefore, in these systems, time is represented as a big number (i.e. the number of seconds passed since 1970-01-01 00:00:00). This is typically referred to as Epoch time, Unix time, Unix Epoch time, or POSIX time. As I write this, Unix time is 1560913841. And as I write this next line, Unix time has incremented to 1560913879.

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How to Return the Unix Timestamp in SQL Server (T-SQL)

Posted on by Ian

You might have noticed that SQL Server doesn’t have an equivalent of MySQL‘s UNIX_TIMESTAMP() function.

However, it’s not that difficult to return the Unix timestamp in SQL Server.

The Unix timestamp (also known as Unix Epoch time, Unix time, or POSIX time) is simply the number of seconds that have elapsed since 00:00:00 Thursday, 1 January 1970, Coordinated Universal Time (UTC). Therefore, in SQL Server we can use a couple of T-SQL functions to return this.

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How to Display a Date in German Format in SQL Server (T-SQL)

Posted on by Ian

When formatting a date using the FORMAT() function in SQL Server, the date will be formatted according to the language of your local session. However, you can override this by specifying a culture to use, or using a custom date format.

This article demonstrates how to explicitly specify a German date format by using the optional “culture” argument of the FORMAT() function. It also demonstrates how to use your own custom date format if that is more desirable.

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How to Display a Date in British Format in SQL Server (T-SQL)

Posted on by Ian

This article demonstrates how to explicitly format a date in Great Britain English format when using the T-SQL FORMAT() function in SQL Server.

You may or may not need to use this argument, depending on the language of your local session. However, here’s how to explicitly specify Great Britain English date format.

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How to Display a Date in US Date Format in SQL Server (T-SQL)

Posted on by Ian

In SQL Server, you can use the T-SQL FORMAT() function to display a date in the desired format. This function accepts an optional “culture” argument, which you can use to specify US date format.

You may or may not need to use this argument, depending on the language of your local session. However, here’s how to explicitly specify US date format.

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WEEK() Examples – MySQL

Posted on by Ian

In MySQL, you can use the WEEK() function to get the week number for a given date. By “week number” I mean the week of the year.

To use the function, simply provide the date as an argument and the week number will be returned.

You also have the option of specifying whether to start the week on Sunday or Monday, and whether the week should be in the range 0 to 53 or 1 to 53.

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