Wait For Data to be ready
Here are two SQL Server based methods for waiting for data, and raising an alert if it’s not ready. I’ve designed them as simple templates which I can easily re-use and customise.
NULL: When a value is neither IN or NOT IN a list.
NULL is always a challenge for equality, I’ve written about it before. I recently produced some samples for training/explanation of NULL when it comes to IN and NOT IN, and thought I’d include it here.
Warning: Null value is eliminated by an aggregate or other SET operation
In data warehousing where aggregation (GROUP BY) is one of the most common things done in queries, we often get the warning: Warning: Null value is eliminated by an aggregate or other SET operation In most cases what is happening is harmless. But what is happening? NULL in aggregation First we have to better understand…
In SQL Server, not all spaces are equal
I recently had a challenge mapping attributes using a lookup table. I had the same customer name in two tables “bobs widgets”, but when I tried to join on the names, there was no match. To cut a long story short, there is more than one way to encode a space. This picks up from the…
Some Refactoring Solutions For Magic Numbers
Today I’m looking at solutions to Magic Numbers. Magic numbers are hard coded numbers (or references) which appear in scripts and procedures, they creep in very easily. I don’t think that magic numbers are entirely bad. If you have a stored procedure which modifies data for a specific customer, having the one customer ID in…
Replacing Repeated Magic Numbers
If an ID or reference is used more than once in a process, it’s best to store it in a variable and reference that. This can slow down debugging, but makes a process far more portable. It also reduces the number of magic numbers in a process (or at least times they are defined). I…
Cleaning Strings: Removing & replacing extra characters
Part of managing data is cleaning text. Tabs, spaces and line breaks can sneak in, and confuse output. When working with whitespace characters and line breaks, we can’t see them. This can cause a lot of confusion for users (and developers) when unexpected behavior occurs. Keep in mind we have to be careful, often we…
Search for text in SQL Procedures & Views etc..
A new project, incomplete documentation, and the original author gone. I need to know “what updates and uses this object?”. So, how do I search for it?. If there is good source control and code management, a simple search will work. In many cases, there isn’t the luxury of code management. Search the code behind…
Managing update differences – NULL and NOT NULL
When are two values the same but different? When they are both NULL. Here I compare equality checks, including my datatype neutral method. The Problem Equality (or lack thereof) between values is an easy check. Is 1 = 3, or is 4 <> 5? Many people (and processes) get unexpected results when they try to…
Number sequences
Here is a quick look at number sequences, which are a brilliant (and fairly database neutral) method to create numbers (and rows) to build datasets from. While working on the dates articles, I used number sequences a lot and thought they were worth coming back to. What is a number sequence A number sequence can…