Category Archives: Data Warehouse

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 OPENROWSET and BULK INSERT (4)

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 The INSERT statement and Column Defaults in Sql Server

“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The spObjectExists procedure has been replaced by TestObjectExists, with the following signature: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 “Test-First” Database Development (2)

“Test-First” Database Development (1)

I’m looking at the practicalities of using Continuous Delivery/Agile techniques where the database is a “high scale” project in Agile terms, and therefore relatively difficult (for more detail about this Agile terminology refer to Scott Ambler’s writings).

As well as thinking about the big issues, I want to start putting together some of the pieces to make it work. I’m doing this in Sql Server 2014 Transact-Sql. I’ve started with automated testing of reporting procedures. There may be utilities that can do this; finding suitable tools is part of the research. It still seems worthwhile having alternatives in Transact-Sql if possible. There’s no purchase or installation to approve, and the code is easy to understand and to edit. Continue reading “Test-First” Database Development (1)

Agile Continuous Delivery of Databases (1)

Agile and Continuous Delivery techniques have been applied to databases for some time, and it’s clear they offer big advantages. Some types of application are particularly suited. They’ll be well-represented among the successes and case studies. Others, such as those including a complex relational database, don’t fit the mould quite so easily. These would be in the “Agility at Scale” category, and often in use within large enterprises.

How does our database project fit in? If Agile wouldn’t be an easy win, can we still get some benefit? I’ve been thinking about that, because the data warehouses I work on are definitely not easy wins. I’m jotting down some notes here, not a formal document, and I hope to develop my thinking in future blogs. Continue reading Agile Continuous Delivery of Databases (1)

Sql Server Collation Cheat Sheet

This post is not written for an architect or DBA who has to choose a collation and wants an in-depth explanation, but for a developer (perhaps one with an error to fix) who needs a primer on the subject.

Put very simply, collations have to do with languages and with the rules used to compare characters. This is relevant in joins and sorting. You might think that a collation ought to be specified for the query; that in your sql statement you should determine the rules to use for comparing values. You can do that (although you’ll set it at column, not query level), but the columns in the tables have a collation property which is what the query uses by default. This is a convenience as it standardises comparisons and saves you having to specify the rules over and over again. It’s when the two conflict that you have an error which may make it necessary to override one or more default collations. Continue reading Sql Server Collation Cheat Sheet

OPENROWSET and BULK INSERT (3)

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This is the promised post about using a Powershell script to inspect large files. It won’t be possible to open a very large file in Excel of course, and some text readers may struggle under the weight of data. This script is an alternative that runs under most if not all versions of Windows, and doesn’t need an installation or a licence. Continue reading OPENROWSET and BULK INSERT (3)