Dealing With NULL

Jeff Mlakar has a pair of comparisons for NULL handling, with ISNULL vs COALESCE and CONCAT vs + for concatenation:

We expect this much from IsNull. However, coalesce is a little different. will take the data type from the first non-null value passed and use that for the table definition. This might not always be what you want because if you pass bits you might get integers. If you pass an array of integers and floats you will get numeric. Be aware if this isn’t what you wanted.

Read the whole thing.

Graph Data In SQL Server

Terry McCann has a first look at SQL Server 2017’s graph data capabilities:

SQL Graph is a similar concept to what is described above, but built in to the core SQL Server engine. This means 2 new table types NODE and EDGE and a few new TSQL functions in particular MATCH(). SQL Graph at the time of writing is only available in SQL 2017 ctp 2.0. You can read more and download ctp2.0 here https://blogs.technet.microsoft.com/dataplatforminsider/2017/04/19/sql-server-2017-community-technology-preview-2-0-now-available/. Once ctp 2.0 is installed there is nothing else you need to do to enable the new graph syntax and storage.

There is an example you can download from Microsoft which is a similar set up to the example in the image above. However I have used some real data shredded from IMDB the internet movie database. This data is available to download from Kaggle https://www.kaggle.com/deepmatrix/imdb-5000-movie-dataset

Click through for a video demonstration as well.

SQL Server Graph Database

The SQL Server team announces graph extensions in SQL Server 2017:

Graph extensions are fully integrated in the SQL Server engine. Node and edge tables are just new types of tables in the database. The same storage engine, metadata, query processor, etc., is used to store and query graph data. All security and compliance features are also supported. Other cutting-edge technologies like columnstore, ML using R Services, HA, and more can also be combined with graph capabilities to achieve more. Since graphs are fully integrated in the engine, users can query across their relational and graph data in a single system.

This is interesting.  One concern I have had with graph databases is that graphs are storing the same information as relations but in a manner which requires two distinct constructs (nodes and edges) versus one (relations).  This seems to be a hybrid approach, where the data is stored as a single construct (relations) but additional syntax elements allow you to query the data in a more graph-friendly manner.  I have to wonder how it will perform in a production scenario compared to Neo4j or Giraph.

Using OUTPUT To Get Change Counts

Manoj Pandey shows how to use the OUTPUT clause to determine the number of records inserted, updated, or deleted after a DML statement:

–> Question:

How can I get the numbers of records affected in the Merge statement, INSERT,UPDATE,DELETE separately and store it in a variable so I can get it in the application side?

Thanks !
–> My Answer:

You need to use OUTPUT clause with MERGE statement

Click through for a code sample.  The OUTPUT clause also works for non-MERGE statements like INSERT, UPDATE, and DELETE, though the “get changes by type” problem is really limited to the MERGE statement.

NOLOCK On CTEs

Erik Darling shows how the NOLOCK hint works with common table expressions:

So, for all you NOLOCKers out there, you can now save yourselves oodles of time by only using the hint in outer references to your CTEs and Views.

Congratulations, I suppose.

(Please stop using NOLOCK.)

Agreed, whenever possible.

T-SQL Variable Scoping

Bill Fellows points out an oddity of T-SQL variable declarations and scoping:

Crazy enough, the last two are correct. It seems that unlike every other language I’ve worked with, all variables are scoped to the same local scope regardless of where in the script they are defined. Demo the first

Wanna see something even more crazy? Check this version out

I should note that I wanted a submit button.

SET NOEXEC ON

Andy Kelly shows how to prevent part of a script from running:

 

If we were to hit F5 (or however you execute your TSQL statements in SSMS) without highlighting any statement(s) they would all be executed, one batch after the other. Even if one batch were to fail or we had a THROW in that batch it would fail at that point but execution would continue immediately after the next GO until the end. This is where SET NOEXEC ON comes into play. If I add that at the beginning of the script all succeeding code would not be executed. The statements would only be compiled and not actually run. It would look like this:

SET NOEXEC ON;

PRINT ‘Got Here 1’ ;
GO
PRINT ‘Got Here 2’ ;
GO
PRINT ‘Got Here 3’ ;
GO
PRINT ‘Got Here 4’ ;
GO

This is a useful “accidental F5” protection:  you can put it at the top of your long script to keep from running the whole thing at once.

U-SQL Deprecation Notices

Michael Rys has a couple pieces of U-SQL syntax which will be deprecated.  First is partition by bucket:

In the upcoming refresh, we are removing the deprecated syntax PARTITION BY BUCKET and will raise an error.

Thus, if you have not yet updated your table definitions with the previously announced new syntax, please do so now or your scripts will fail starting some day in February!

The second post involves credentials:

Back in October, we announced that we simplified the U-SQL Credentials by merging the password secrets that are being created in Powershell and the other parts of the credential object into credentials that are being completely created with a Powershell command. This reduces one statement from the creation process.

During the initial phase, we did provide support for both kinds of credential objects, and still supported the old syntax.

In the upcoming February refresh, we are now automatically migrating the existing old credentials into the new format and remove the CREATE CREDENTIAL, ALTER CREDENTIAL and DROP CREDENTIAL statements.

If you’re writing U-SQL code, you’ll want to read up on the ramifications and alternatives here.

CONCAT_WS()

Manoj Pandey points out a new string function in SQL Server vNext:

Here in this post I’ll discuss about one more new function i.e. CONCAT_WS(), here “_WS” means “With Separator”.

This is very similar to the existing CONCAT() function introduced back in SQL Server 2012, which concatenates a variable number of arguments or string values.

The difference is the new function CONCAT_WS() accepts a delimiter specified as the 1st argument, and thus there is no need to repeat the delimiter after very String value like in CONCAT() function.

It’s a small change, but I think a rather useful one.  Do think about how you’d want to interpret NULL values, though, as CONCAT_WS() does not include separators for NULL values.

Multiple Operations Per Command

Louis Davidson points out a potential query writing time-saver:

But then I saw Mike use the following syntax (sans PROFILE and XML):

SET STATISTICS IO, TIME, PROFILE, XML ON;
GO
SELECT *
FROM   dbo.Table1;
GO
SET STATISTICS IO, TIME, PROFILE, XML OFF;

Wow, that is a lot easier! (And yeah, using SQL Prompt I can set a snippet to take away typing, but this saves space in any case.)

Read on for more examples.

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