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Category: T-SQL

Finding the Actual Error Line in sp_executesql

Published 2023-06-23 by Kevin Feasel

Thom Andrews solves a problem:

Notice that the error line states line 2 not line 8, which is the line the sys.sp_executesql was called on. Knowing the line the error occured on within the dynamic batch is certainly important, but if you’re working with multiple dynamic batches you have no way of knowing which dynamic batch might have produced the error; was it the one executed on line 100? Line 200? Line 350?

Solving this problem wasn’t wasn’t exactly simple, and it came with a couple of caveats.

Click through for the approach. As Thom mentions, it isn’t perfect, but it is reasonable and interesting.

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The Value of QUOTENAME

Published 2023-05-31 by Kevin Feasel

Quoth Chad Callihan, “Occasionally more”:

QUOTENAME can be used to make sure database objects are valid in your query. Most of the time, objects like table names only contain valid characters, so there’s nothing to worry about. But nobody’s perfect. Let’s look at an example of what can happen when somebody creates a table with a forward slash in the name and see how QUOTENAME can be used to query against it.

QUOTENAME is also a good way of preventing SQL injection, though I still prefer appropriate use of exec sp_executesql in any case in which it’s possible to use.

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Filling Gaps in T-SQL

Published 2023-05-30 by Kevin Feasel

Itzik Ben-Gan has a new challenge:

The task involves developing a stored procedure called GetBalances that accepts a parameter called @accountid representing an account ID. The stored procedure should return a result set with all existing dates and balances for the input account, but also gap-filled with the dates of the missing workdays between the existing minimum and maximum dates for the account, along with the last known balance up to that point. The result should be ordered by the date.

My first thought was last observation carried forward, which is now available in SQL Server 2022 (Itzik’s solution 2). I kind of thought of solution 3, though did not think through the mechanics of how it’d work and so I get no credit there.

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Trying NTILE

Published 2023-05-17 by Kevin Feasel

Chad Callihan looks at the fourth ranking window function:

Have you ever used the NTILE function? Or have you even heard of the NTILE function? It seems to be one of the lesser known, lesser used window functions in SQL Server. I’ve never come across it in the wild but maybe there are those that use it all the time. Either way, let’s have a look at what it does and how it can be used.

Click through for a demo. I definitely use it a lot less than ROW_NUMBER(), RANK(), and DENSE_RANK(), but I have used it to some good effect in the past, mostly in cases where I’ve wanted to focus on the top X% of data for an analysis.

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Choosing from a List of Values

Published 2023-05-10 by Kevin Feasel

Greg Dodd doesn’t need no steenkin’ tables:

Sometimes you have a list of values or parameters that you’d like to run a select statement over the top of to get a result. There’s a few ways of doing this, usually I see people create a Temporary Table and insert the data. But is there an easier way?

Yes, we can select from VALUES:

The result of this is called a virtual table, and as far as other parts of the query are concerned, it’s just another table.

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Adding a UTC Time Zone Indicator to a Date in SQL Server

Published 2023-05-04 by Kevin Feasel

Bill Fellows fights with the language:

It seems so easy, I was building json in SQL Server and the date format for the API specified it needed to have 3 millsecond digits and the zulu timezone signifier. Easy peasy, lemon squeezey, that is ISO8601 with time zone Z format code 127

SELECT CONVERT(char(24), GETDATE(), 127) AS waitAMinute; Running that query yields something like 2023-05-02T10:47:18.850 Almost there but where’s my Z? Hmmm, maybe it’s because I need to put this into UTC? SELECT CONVERT(char(24), GETUTCDATE(), 127) AS SwingAndAMiss;

Running that query yields something like 2023-05-02T15:47:18.850 It’s in UTC but still no timezone indicator.

Read on for several attempts and what finally did the trick.

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CETAS in SQL Server 2022

Published 2023-05-04 by Kevin Feasel

Eric Rouach shows off a nice extension to T-SQL in SQL Server 2022:

Create External Table As Select or “CETAS” has finally become available on SQL Server with the release of the 2022 version.

After a short setup, we can create various formats files containing any query’s result set. The created file/s must be kept on an Azure storage solution i.e. Azure Blob Storage.

The process also creates an external table reflecting the updated file’s content.

We’ve been able to do this in Azure Synapse Analytics dedicated and serverless SQL pools for a while, so it’s good to be able to create an external table from a SELECT query on-premises, especially considering that it’s the only way we have left to write to external sources using PolyBase.

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