The Bit Bucket

Several times now on forums, I’ve seen questions about Change Data Capture (CDC). People like the way they can retrieve details about changes that have occurred (often to trickle-feed into a data warehouse), but they are puzzled why CDC doesn’t tell them when the event occurred. There’s an easy fix for that.

Let’s start by doing a quick CDC setup:

DROP DATABASE IF EXISTS CDC;
GO

CREATE DATABASE CDC;
GO

USE CDC;
GO

CREATE TABLE dbo.NewEmployees
( 
    NewEmployeeID int IDENTITY(1,1) PRIMARY KEY CLUSTERED,
    FullName nvarchar(100)
);
GO

-- note new last few columns in:

SELECT * FROM sys.databases WHERE name = N'CDC';

-- enable cdc at the database level

EXEC sys.sp_cdc_enable_db;

-- enable cdc for the table - requires SQL Agent running

EXEC sys.sp_cdc_enable_table
  @source_schema = 'dbo',
  @source_name = 'NewEmployees',
  @supports_net_changes = 1,
  @role_name = NULL;

-- review the state of CDC

SELECT name, is_tracked_by_cdc FROM sys.tables;
GO

And let’s then add three rows of data, then change one of them:

2020-05-14

The DateDimensionColumns function in our free SDU Tools for developers and DBAs, has been really popular. It provides the standard columns that are part of a typical date dimension in a data warehouse. But we’re especially proud of a new function that can be used to expand a date dimension with really useful additional information. We call it DateDimensionPeriodColumns.

The DateDimensionColumns function had the usual columns:

Date, Day Number, Day Name, Short Day Name, Month Name, Short Month Name, Month Number, Month Label, Year, Year Label, Day of Year, Fiscal Month Number, Fiscal Month Label, Fiscal Year, Fiscal Year Label, Day of Fiscal Year, ISO Week Number

2020-05-13

Most websites that I visit have a link at the bottom of the page that suggests that you can use it to contact either the website team or the company that owns the site. (Might not be the same people) Based on years of trying, my expectation of ever getting a response from using one of these links is close to zero.

If you have a website that has a contact link, does it lead anywhere sensible?

2020-05-12

When you’re writing T-SQL code, it’s really common to need to extract components of a date, and the most common need is for year, month, and day. So T-SQL has separate functions just for that.

You can see the output from this query here:

The YEAR(), MONTH(), and DAY() functions take a date (or datetime, datetime2, smalldatetime) as input and return an integer for the year, month, or day.

2020-05-11

I’ve seen questions on the forums asking about where localdb stores its database files. Often, the question is about how to stop them going into the C:\Users folder. Clearly, that doesn’t seem to be a good spot for them.

localdb stores database files in the C:\Users area by default as it’s trying to find a location that the current user will have permission to write to. While I understand the rationale, that’s not where most users will want those files.

2020-05-08

There’s a question that I hear all the time in SQL Server forums:

Why didn’t the transaction roll back when a primary key violation occurred?

Take a look at the code in the main image above. Would you expect it to execute the second and third INSERTs if the first INSERT failed with a primary key violation? So many people would. If you’re one of them, read on.

By default, that’s not how SQL Server works.

2020-05-07

I recently came across a requirement to extract someone’s initials from within their name. That was a new one for me, so we added a new function into our free SDU Tools for developers and DBAs. It’s called InitialsFromName.

It’s a straightforward scalar function that takes two parameters:

@Name nvarchar(max) is the name to extract the initials from

@Separator nvarchar(max) is a separator placed between the returned initials.  (Make it an empty string for none)

2020-05-06

I hear about frequent drive-by shootings in some countries. Fortunately that doesn’t happen where I live. But what I come across all the time on Q&A forums, is what I’d like to call DBTs (Drive by trashings).

It usually starts when someone makes a genuine effort to try to help answer a question. The DBT (drive-by trasher) pops in and leaves a nasty unhelpful message. It could be “That’s misleading” or “That’s wrong” or “You don’t understand how it works”.

2020-05-05

It’s really common to need to know the current date and time in T-SQL code. Ever since the beginning of the SQL Server product, we’ve had a function called GETDATE(). It returns the current date and time of the server as a datetime value.

In SQL Server 2008, we got new higher precision data types, and so new current date and time functions were added as well.

SYSDATETIME() is a function that returns the current date and time as a datetime2 value. And SYSDATETIMEOFFSET() returns the timezone offset for the server as well.

2020-05-04

Today I wanted to call out a common mistake that I see at websites all over the country. Don’t add pages to your website if you’re not going to update them.

I’m particularly talking about pages with names like “News”, “Articles”, “Blog Posts”, etc. They’re often added when someone first builds a website and is full of hope for how it will be used.

And then it isn’t.

Old News

I’ve lost count of how many sites I visit where there’s a News section and when I visit it, there are two or three entries, often years apart. Or worse, there are a few entries from five years ago when the website was first created.

2020-05-01