CROSS APPLY with Ranking and Analytical Functions

As I posted here, I’m very interested in using CROSS APPLY in a new way to keep down clutter in sql statements with complex column expressions. I recently found a limitation. I think I’ve figured out why, and since understanding reduces frustration I’m posting it here. Continue reading

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OPENROWSET and BULK INSERT (4)

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Here are some final notes on this topic. I’m going to describe an import I did recently, and hope this may help you decide where OPENROWSET and BULK INSERT could fit into your development activity and what tools you might use.

I was doing an ad hoc load of some data from a small csv file. There was no corresponding table in the database to store this data, and I don’t like doing work for the sake of it, so my first stop was the “Sql Server 2014 Import and Export Data” wizard. I was hoping it would be a simple matter for the wizard to build a table and read the data into it. It crashed with an error which wasn’t very specific. Continue reading

Cost-Based (Design) Optimisation

No, not the Oracle Cost-Based Optimizer – this is about optimising your design for (financial) cost; and no, it doesn’t mean that we as developers need to be worrying about pennies while we’re coding, or even that we have much influence on costs.

It’s just an interesting remark from a podcast by Brent Ozar here. At 20 minutes 14 seconds in, Continue reading

Agile Continuous Delivery of Databases (2)

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Most applications include a database, and the goal of the project I’m working on is to make Agile continuous delivery possible in the database as well as in procedural code. The peculiar problem with databases is that when a change deployment fails we risk losing data that has been added since the release.

The “blue-green” deployment model is a way of dealing with this. We cut over to an “old version” database. The code and schema of this database pre-date the release, but it has received all the data changes since the release.

How can this be? Continue reading

The INSERT statement and Column Defaults in Sql Server

When you INSERT into a table which has a column with a default value defined, and you omit that column from your statement, what will happen? The default will be written. What if you write an explicit Null (and the column is nullable)? In nearly all cases the Null is written.

You may not want this – it’s one of the cases where it might be nice if there were more than one type of Null, as some people advocated in the early days. Then we could distinguish a “known unknown” (© D. Rumsfeld) Continue reading

Complex T-Sql Column Expressions? You must try this!

There’s an outstanding video by Kendra Little called “5 T-Sql Features You’re Missing Out On” which you can reach from my Links (Topical) page under “Database > Transact-Sql”. It describes a special way of using the CROSS APPLY statement in T-SQL. This is a technique that can change the way you write Sql, or at least it can in cases where you have an expression that is used in several columns of a SELECT statement. Continue reading

“Test-First” Database Development (2)

I’ve made additions and changes to the GitHub repository for “Test First” development of the database schema. All procedure names will now start with “Test”, so that they’re easier to find in Object Explorer and Intellisense. I’ve added a “TestHeader” stored procedure. You can put this at the top of your TDD script and it’ll add the date/time, database user, Sql Server version etc., to your results.

The spObjectExists procedure has been replaced by TestObjectExists, with the following signature:
CREATE PROCEDURE [dbo].[TestObjectExists]
@i_ObjectType sysname
,@i_ObjectName sysname = Null
,@i_ParentSchemaName sysname = Null --not needed if testing schema's existence
,@i_DbName sysname = Null
AS
Continue reading