Aggregating date and time values

Date and time values are not entirely intuitive to aggregate into averages in T-SQL, although the business case does arguably exist. Suppose, for instance, that you have a production log with a “duration” column (in the “time” datatype), and you want to find the totalt or average duration for a certain group of items.

It’s possible, but I would still call it a workaround.

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Anonymize your dev databases!

I’ve been working on a little gadget for a while now, and today I finally got around to completing it and so now I’ve published it for everyone to try out. It’s a web API (wait, wait, don’t go away – it’s for database people!) that creates a randomized list of names, addresses, etc.

In this post, I’ll show you how easy it is to use this service to anonymize a development or test database so you don’t have all that personally identifiable information floating around.

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CAST/CONVERT makes expressions nullable

I came upon this issue when I was building some views to support legacy integrations to an app that I was refactoring. The view is supposed to have exactly the same column definitions as a table in the old database that I am redesigning, so to make SSIS packages and other integrations run smoothly, I want the view’s columns to have the same datatypes, nullability, etc.

But there are some gotchas to watch out for with CAST and CONVERT.

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Quick and dirty: How to right-align numeric columns in SSMS

Here are 50 random numbers:

--- 50 random numbers
WITH cte AS (
SELECT 0 AS i, 100000.*POWER(RAND(CHECKSUM(NEWID())), 3) AS n
UNION ALL
SELECT i+1, 100000.*POWER(RAND(CHECKSUM(NEWID())), 3)
FROM cte WHERE i<50)

SELECT *
FROM cte;

And in SSMS, with the variable-width default font, the output looks… slightly-less-than-readable in the grid view:

We could use STR() to format the output, but the indent looks a little off:

--- 50 random numbers
WITH cte AS (
SELECT 0 AS i, 100000.*POWER(RAND(CHECKSUM(NEWID())), 3) AS n
UNION ALL
SELECT i+1, 100000.*POWER(RAND(CHECKSUM(NEWID())), 3)
FROM cte WHERE i<50)

SELECT *, STR(n, 12, 2) AS with_str
FROM cte;

Here’s something I’ve found: the space character is roughly about half the width of a typical number character. So replace every leading space with two spaces, and it will look really neat in the grid:

--- 50 random numbers
WITH cte AS (
SELECT 0 AS i, 100000.*POWER(RAND(CHECKSUM(NEWID())), 3) AS n
UNION ALL
SELECT i+1, 100000.*POWER(RAND(CHECKSUM(NEWID())), 3)
FROM cte WHERE i<50)

SELECT *, STR(n, 12, 2) AS with_str,
       REPLACE(STR(n, 12, 2), ' ', '  ') AS with_replace
FROM cte;

(and terrible everywhere else, obviously.)

Get the join cheat sheet!

Download and print this nifty little PDF with all of the INNER, LEFT, RIGHT, FULL and CROSS JOINs visualized! It’ll look great on your office wall or cubicle. Your coworkers and your interior decorator will love you for it.

How it works: For each join example, there are two tables, the left and the right table, shown as two columns. For the sake of simplicity, these tables are called “a” and “b” respectively in the code.

You’ll notice that the sheet uses a kind of pseudo-code when it comes to table names and column names.

Speaking at the Group By conference!

This past Friday, I had the great privilege of speaking at the on-line Group By conference. Group By is a community-driven conference where anyone can submit an abstract. Site visitors will then rate sessions as well as help you build and improve your abstract.

My presentation was about various tips and tricks in SQL Server Management Studio, some of which I’ve already covered in previous articles on this blog.

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