Tag: SQLNewBlogger

There is a SET command in SQL Server that changes how much data is returned from some fields. This short post shows what I learned about the SET TEXTSIZE command.

Another post for me that is simple and hopefully serves as an example for people trying to get blogging as #SQLNewBloggers.

The Scenario

Let’s start with a little code. I actually created a table that looks like this:

CREATE TABLE [dbo].[Beer]

(

[BeerID] [int] NOT NULL IDENTITY(1, 1),

[BeerName] [varchar] (20) COLLATE SQL_Latin1_General_CP1_CI_AS NULL,

[brewer] [varchar] (20) COLLATE SQL_Latin1_General_CP1_CI_AS NULL,

[beerdescription] [varchar] (max) COLLATE SQL_Latin1_General_CP1_CI_AS NULL

) ON [PRIMARY] TEXTIMAGE_ON [PRIMARY]

GO

I added data so that I have something in here:

INSERT INTO dbo.Beer
   (BeerName, brewer, beerdescription)

VALUES
  (1,    'Becks', 'Interbrew', 'Beck''s is a German-style pilsner beer known for its golden color, full-bodied taste, and a crisp, clean finish with floral and fruity hop aromas, brewed according to the German purity law')

,(2,    'Fat Tire', 'New Belgium    Toasty malt, gentle sweetness, flash of fresh hop bitterness. The malt and hops are perfectly balanced.')

,(3,    'Mac n Jacks', 'Mac & Jack''s Brewery', 'This beer erupts with a floral, hoppy taste, followed by a well rounded malty middle, finishing with a nicely organic hop flavor. Locally sourced two row grain and a blend of specialty malts give our amber its rich taste.')

,(4,    'Alaskan Amber', 'Alaskan Brewing', 'Alaskan Brewing Amber Ale is an "alt" style beer, meaning it''s fermented slowly and at colder temperatures, resulting in a well-balanced, richly malty, and long-lasting flavor profile with a clean, pleasing aftertaste.')

,(8,    'Kirin', 'Kirin Brewing', 'Kirin Ichiban is a Lager-type beer, which means it is fermented at low temperatures and offers a light and refreshing texture with a smooth and balanced flavor.')

Now, let’s see what this setting does.

SET TEXTSIZE

This command changes the behavior of SELECT queries and controls how much data is returned in bytes. The setting is the command with an integer after it. The max value is 2GB.

I’ll run a normal query, then I’ll set a smaller size and repeat the query. Notice how the results differ below. I get less data in the second query.

What this setting does is limit the number of bytes from some fields. I only have 20 characters from each description.

Let’s do one more query. I’ll lower the value to 5.

Note that while the description is very low, the name and brewer are not cut off.

The explanation is that this works on the max types: varchar(max), nvarchar(max), varvinary(max), text, ntext, and image. Non-max fields aren’t affected.

Also note that the default setting from the SQL Native Client and ODBC driver is –1, for unlimited data. That explains why I haven’t noticed this as I’m often using an app that uses one of those. IF you set this to 0, then it defaults to 4KB.

A nice way to prevent apps from grabbing tons of data unless they need it, though you’d certainly need to help users understand why they weren’t getting all the data expected. I think long fields (or image/audio/etc. data) would need a “get more” or “get all” item in software to reset this and return the full value in the table.

SQL New Blogger

This was a function I ran across, whose purpose I had no idea about. I read it, experimented, and in about 30 minutes had put together this demo and post. Easy to do and quick.

I learned something, and I’m sharing this with potential employers. You could as well, with a little effort.

We recently published an article on CHOOSE at SQL Server Central. I thought it was a good intro, but as someone noted in the comments, how do you use CHOOSE? Do you have to hard code choices?

This post shows you don’t.

Another post for me that is simple and hopefully serves as an example for people trying to get blogging as #SQLNewBloggers.

A Scenario

I have a table that contains some data. In this case, about beer. I like beer, and this was a fun little demo. I’m not recreating the DDL because, well, you might like different beers.

In any case, this is simple to set up.

If I wanted to choose some data from this table based on an index, I could do something like this. This code populates the first index in choose with beers and the second with brewers. CHOOSE is 1-based indexing.

DECLARE @i INT = 1;
SELECT
   CHOOSE (@i, beername, brewer)
FROM dbo.Beer AS b2;

This returns me the beers.

If I changed the value to 2, I get brewers. I show both below.

How would I use this? Maybe a user is asking to edit either a home or shipping address. I can index these by returning the column data as index 1 or 2, and linking the user suggestion to the index. They choose home, we pass in 1. If we qualify the query with a WHERE clause to one customer, they get just their data to edit.

I could even do something silly, like getting values from different places. For example, here I’ll use string_split on a value.

DECLARE @i INT = 2;
DECLARE @s VARCHAR(20) = 'Vodka,Tequila,Bourbon'

; WITH a (value)
AS
(SELECT a.value FROM STRING_SPLIT(@s, ',', 1) AS a
  WHERE a.ordinal = 1
),
  b (value)
AS
(SELECT a.value FROM STRING_SPLIT(@s, ',', 1) AS a
  WHERE a.ordinal = 2
),
  c (value)
AS
(SELECT a.value FROM STRING_SPLIT(@s, ',', 1) AS a
  WHERE a.ordinal = 3
) 
SELECT
   CHOOSE (@i, a.value, b.value, c.value)
  FROM a, b, c

This is silly, but it does return an acceptable answer.

I don’t know that there are many places that I’d use CHOOSE, but as I play with it, I can see that it could be a handy tool at times with a little creativity.

SQL New Blogger

This post took me about 15 minutes to write after I saw a comment. I set up a scenario and posted a reply, then took that code to structure this post. The STRING_SPLIT piece was the longest, as I had to futz with code, but I show some use of a new feature and how I might incorporate this into an application.

You could write your own creative blog on this, probably in 30 minutes or less. I bet you’d get asked about this in an interview as it’s kind of funny.

This was an interesting thing I saw in a Question of the Day submission. I hadn’t thought about the issue, but apparently DATEADD truncates values rather than rounding them. I’m not sure why that is the case, but it is.

Another post for me that is simple and hopefully serves as an example for people trying to get blogging as #SQLNewBloggers.

The Scenario

Imagine that I have someone enter a value for the number of hours to include in a report. I enter 5 and the report divides this in half to go back 2.5 hours and forward 2.5 hours. I run this code at the top of my code block:

DECLARE @hours NUMERIC(4, 2) = 5;
DECLARE @start DATETIME, @end datetime
SET @start = DATEADD (hour, -@hours / 2, GETDATE ())
SET @end = DATEADD (hour, @hours / 2, GETDATE ())

Now, what do you think are the resulting start and end times? I’d assume this works and the function sorts out how much of an hour is .5 or .4 or whatever.

Here’s the interesting result. Look at the time interval in the end result.

It’s 4. I entered 5 hours, but I get 4 hours. I bet a lot of us would let this bug slip through as reading the datetimes we’d miss this wasn’t actually 5 hours.

Apparently DATEADD actually truncates a non-integer value. The parameter notes that the 2nd parameter, the number to add to the date value, resolves to an integer. It also notes that DATEAD truncates, not rounds, values that have a decimal fraction.

Those are two very important distinctions. That could result in calculations that are way off from what people expect if you are trying to include data in a query and you are trying to do parts of time. You might need to separately calculate all your different date/time parts.

If you need to do fractional work with dates, you can’t use DATEADD.

To me that seems lacy, but is it? Let me know.

SQL New Blogger

This is a short example of something that a person pointed out to me, and I never knew. I decided to make a quick test (the code above) and then write about this. I could have included other examples, or shown how this might mess up different situations in my code.

You could do the same thing in 30 minutes or less and point out an interesting piece of knowledge that your future employers might find interesting. They might even want to interview someone that learns things like this.

Recently I was talking with someone who had not named any of the primary keys (PKs) in their database. They used system generated names and when they ran comparisons, they got all sorts of drops and creates they didn’t expect. This post shows how easy it is to declare PKs with names, even with complexity.

Another post for me that is simple and hopefully serves as an example for people trying to get blogging as #SQLNewBloggers.

The Scenario

I’m going to use a schema that I have for baseball data. It illustrates the point well, I think.

For my friend, imagine a table like this one:

CREATE TABLE [dbo].[salaries](
     [yearID] [int] NOT NULL,
     [teamID] [varchar](3) NOT NULL,
     [lgID] [varchar](2) NOT NULL,
     [playerID] [varchar](9) NOT NULL,
     [salary] [int] NULL,
PRIMARY KEY CLUSTERED 
(
     [yearID] ASC,
     [teamID] ASC,
     [lgID] ASC,
     [playerID] ASC
)
)

If I create this table, the system will decide what the PK is. In fact, after I run this, I can see in sys.objects that the name is some random code.

What’s worse is that if this were an FK and I were dropping these in some script, I’d have issues in other systems. This name is different on each system.

The better solution is to make a simple change. Before the Primary Key keyword, I can add Constraint and a name, like this:

CREATE TABLE [dbo].[salaries](
     [yearID] [int] NOT NULL,
     [teamID] [varchar](3) NOT NULL,
     [lgID] [varchar](2) NOT NULL,
     [playerID] [varchar](9) NOT NULL,
     [salary] [int] NULL,
CONSTRAINT salariesPK PRIMARY KEY CLUSTERED 
(
     [yearID] ASC,
     [teamID] ASC,
     [lgID] ASC,
     [playerID] ASC
)
)

If I run this, then I have a better named PK.

Be explicit in your work. It makes for better code and easier, repeatable, reliable deployments.

SQL New Blogger

This is a simple thing, a code smell, but one that wastes DBA and developer time. This post shows a simple thing you can do to have better code. This took me about 10 minutes and you could do something similar.

Write this and maybe someone asks you how to do this in an interview.