In an earlier post, I showed how you can use the YEAR, MONTH, or DAY functions to extract those parts of a date. But what if you want to extract any one of those other intervals?
Well, that’s what the DATEPART function does. It allows us to specify the interval that we want to extract. Look at the following query examples:
And here are the results of that query:
2020-03-02
If you have worked with larger tables in either Power BI or Analysis Services, you’ll know that developing against them is painful. Any time the data needs to be refreshed (which happens often), you spend a lot of time sitting around waiting for it to happen.
Now our buddy Chris Webb proposed a way of getting sampled data during development. That’s pretty good. And fellow MVP Marc Lelijveld also uses a similar method.
2020-02-28
I’ve mentioned before that I really don’t mind working with large tables. They’re only slow to use if you’re looking through all the rows when trying to find the data that you want. But there is still sometimes a valid need to archive data from a main table, across into an archive table. And people often run into problems, particularly blocking problems, when they try to do that.
Let’s start with an example pair of tables (much simplified for clarity):
2020-02-27
The DateDiffNoWeekends tool in our free SDU Tools for developers and DBAs, has been really popular. Another request that we received though, was how to calculate which date a particular numbers week day is. For example, we might want to know which is the 12th week day of the month. So we’ve added a tool to do that. It’s called WeekDayOfMonth.
It’s a function that takes three parameters:
@Year is the year (of the month in question) @Month is month in question (as a number within a calendar year i.e. March = 3) @WeekdayNumber is an integer that gives you the position in the month that you are trying to calculate.
2020-02-26
I work with a lot of different software houses. Microsoft calls these ISVs (Independent Software Vendors). They develop applications that we all use day to day.
When I look at their code, many developers have tried to write database-agnostic code. They might be working with SQL Server today, but want to be able to use Oracle, or Cassandra, etc. without changing code.
As a concept, that sounds great. Why would you want to tie yourself into a specific vendor?
2020-02-25
When you’re working with T-SQL, it’s common to need to work out how far apart two dates and or times are. Look at the query below:
In this case I’m asking how many days is it from 28th of February 2019 to 31st of July 2019? And if look at the answer:
We can see that it’s 153 days.
Now I used days here but now we could have used any of those other intervals that I discussed when we looked at DATEADD. So I could work at how many minutes that was or how many seconds that was between the two times. I could even say how many months?
2020-02-24
I’ve been working a lot with ADF (Azure Data Factory) again lately. If you’ve started to work with ADF and aren’t using Git in conjunction with it, you need to change that now.
ADF objects are also represented as JSON objects and lend themselves nicely to being stored in Git.
Another key advantage is that if you don’t have Git connected, when you’re working with ADF, you don’t have a Save button. If you’re part way through making changes, you can either Publish them or Discard All. When you have Git in place, you get an option to Save.
2020-02-21
There was a question on Stack Overflow recently about SQL Server being “stuck” in single user mode.
The poster had a SQL Server 2016 instance, running on Windows Server 2016. He said he tried to do this:
ALTER DATABASE MyDatabase
SET MULTI_USER;
But it always told him that the database is in use.
The core concept to understand here is that when a database is in single user mode, you can’t assume that you’re the single user. In this case, he clearly wasn’t.
2020-02-20
While it’s not 100% required, your life is generally better if your databases are set to the maximum database compatibility level that your server supports. But it’s a bit of a pain to actually make that change. So in our free SDU Tools for developers and DBAs, we have a procedure that does just that. It’s called SetDatabaseCompabilityForAllDatabasesToMaximum.
It’s a stored procedure and takes no parameters at all.
It checks all the user databases and sets them to the maximum level allowed by the server that they are attached to. It is applicable to SQL Server only. (This procedure doesn’t exist in the Azure SQL Database version of the tools).
2020-02-19
I don’t like seeing abbreviations used when there’s no need to have them. Abbreviations can be overused and many times they’re cryptic. Worse, I often see them applied inconsistently.
In general, I try to avoid abbreviations unless they are on a tight list of ones that I use all the time.
A pet dislike of mine is seeing them used (even if consistently) for interval values in T-SQL functions like DATEADD, DATEDIFF, etc.
2020-02-18