# Tuesday, November 13, 2007

Bah, for the forth time in a week I encounter a star in the select-list of a view. So if no-one told you yet; when creating views, don’t do a SELECT * FROM source, it can (and in time will) hurt you badly. Let’s show by creating a table and two views based on that table;

CREATE TABLE tblSource(
    Col1 nchar(10),
    Col2 nchar(10))
GO
CREATE VIEW vwBad
AS
SELECT * FROM tblSource
GO
CREATE VIEW vwGood
AS
SELECT Col1, Col2 FROM tblSource
GO
INSERT tblSource (Col1, Col2) VALUES ('Column 1', 'Column 2')
GO

So far, so good. Selecting from both views shows you the expected results:

SELECT 'vwGood' view_name, * FROM vwGood
GO
SELECT 'vwBad' view_name, * FROM vwBad
GO

Now add a column to the table, and add some data for that column;

ALTER TABLE tblSource
    ADD Col3 tinyint
GO
UPDATE tblSource
SET Col3 = 3
GO

SELECT 'vwGood' view_name, * FROM vwGood
GO
SELECT 'vwBad' view_name, * FROM vwBad
GO

vwGood still behaves as expected, but vwBad doesn’t return ALL columns as you may have expected based on the *. Now let's see what happens if a column is removed from the table;

ALTER TABLE tblSource
    DROP COLUMN Col2
GO

SELECT 'vwGood' view_name, * FROM vwGood
GO
SELECT 'vwBad' view_name, * FROM vwBad
GO

You will notice that vwGood throws an error (rightfully so, it is instructed to select from a non-existing column), but vwBad doesn’t… it pretends Col3 is Col2. Based on the data, we know better. However this might not be so obvious if based on this change the purchase price is shown as sales price due to changes in the data model and your company starts losing money.

I bet now you want to know which views contain * so you can code them properly, try this query if you're on SQL Server 2005:

SELECT v.name view_name
    , s.name schema_name
    , u.name user_name
    , v.create_date
    , v.modify_date
    , sc.text
FROM sys.views v
    INNER JOIN sys.syscomments sc ON v.object_id = sc.id
    INNER JOIN sys.schemas s ON v.schema_id = s.schema_id
    INNER JOIN sys.sysusers u ON s.principal_id = u.uid
WHERE sc.text LIKE '%*%'

And this one for SQL Server 2000:

SELECT so.name view_name
    , u.name user_name
    , so.crdate create_date
    , sc.text
FROM dbo.sysobjects so
    INNER JOIN dbo.syscomments sc ON so.uid = sc.uid
    INNER JOIN dbo.sysusers u ON so.uid = u.uid
WHERE sc.text LIKE '%*%' AND v.type = 'V'

And don't forget to clean up the example:

DROP VIEW vwGood
GO
DROP VIEW vwBad
GO
DROP TABLE tblSource
GO

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Tuesday, November 13, 2007 12:35:23 PM (W. Europe Standard Time, UTC+01:00)
# Friday, November 9, 2007

As I wrote before, I passed my beta-exam and am well underway. Because of my experience preparing for the exam, the folks from NewLevel asked if I could do a presentation for them on Windows Server 2008... for marketing sake.

I said yes, so if you're interested, available on November 27th (13:30 - 16:00) and can be in Amersfoort:

  • Overview of product features and why you might want to use them.
  • How these features map to the new generation certifications and what this new generation certification could mean to you.
  • Training options to prepare for the Windows Server 2008 certifications and job-roles.
  • Besides all the talking, a demonstration deploying Network Access Protection in Windows Server 2008.

If you're interested, contact NewLevel by phone +31 73 599 0 150 or mail to Rein Floris at NewLevel. The presentation will be in Dutch an a small fee is charged.

Friday, November 9, 2007 8:05:57 PM (W. Europe Standard Time, UTC+01:00)
# Monday, November 5, 2007

Just visited the prometric-website, I've passed my 71-649. Also did a quick check on my MCP-transcript, but it's not showing there, yet! The preparation paid off.

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Monday, November 5, 2007 11:06:34 PM (W. Europe Standard Time, UTC+01:00)

If an SQL Server 2005 database has multiple snapshots, do the first changes get written to all snapshots or only to the most recent? Good question, let's make the answer:

The following scenario is based on this sql-script. It assumes you have the AdventureWorks and your database engine uses C:\Program Files\Microsoft SQL Server\MSSQL.1\MSSQL\Data. Be careful, the script changes some data in AdventureWorks, so some examples from books-online may behave unexpected after this demo.

The scenario is in four stages;

  1. The first snapshot is created and a query displays the sizes of the snapshot file on disk (BytesOnDisk) and the internal size (BytesWritten).
  2. Person.Contact is updated, the Firstname and LastName for all records are swapped, practically resulting in the whole table being written to the snapshot before the update. Right after this update, the second snapshot is created and the query again shows the information about the (now 2) snapshots. The first snapshot holding the Person.Contact table before the update, the second being still empty.
  3. Person.Address is updated, AddressLine1 and AddressLine2 are swapped (and NULLs for AddressLine2 are set to empty strings). The query following this update shows both snapshots have grown, proving all snapshots get written (and we have the answer!!!).
  4. To show a snapshot only processes the changes once since it was created, the FirstName and LastName columns in Person.Contact are swapped again. This time, only the second snapshot gets written to (you may notice one or two data pages (8192 bytes) being added to the first snapshot, an insignificant change compared to previous changes).
Monday, November 5, 2007 10:36:03 PM (W. Europe Standard Time, UTC+01:00)
# Monday, October 29, 2007

Today's question of the course (2780B), how do licensing options mix with multiple instances. The course points out the choices on installation;

  • Per processor
  • Per Server
    • Device Client Access License
    • User Client Access License

That's about it, but as always, MS-Licensing is more complicated than a single page in the text-book. If you want to know it all, there is an SQL Server licensing white-paper, covering;

  • Virtualization / Multi-instances
  • Multi-core processors
  • Fail-over technologies (Cluster, Database Mirroring, Log Shipping)
  • Multiplexing
  • Separation of components over multiple servers.
  • SQL vs Workgroup CAL's
  • Special programs for ISV's and hosting providers
  • Downgrading

For just Virtualization and Multi-instancing, read this section of the above white-paper. For more info on licenses and pricing, visit How to buy SQL Server. Keep in mind that pricing and licensing may vary based on your location.

Monday, October 29, 2007 6:23:37 PM (W. Europe Standard Time, UTC+01:00)
# Thursday, October 4, 2007

... and other Microsoft exams. Since it's Microsoft's objective to have Performance Based Testing (a.k.a. simulations) in all MCTS exams, you'll want to have some peace of mind as to how they are scored (and about the relevance towards the total exam).

Read the full story at Trika's blog, I'm pretty sure more questions and answers will appear in the comments.

Thursday, October 4, 2007 10:20:32 AM (W. Europe Daylight Time, UTC+02:00)
# Sunday, September 30, 2007

Seems I wasn't the only disappointed person who found out WLinstaller sucks on x64. No worries though, I won't have to hack the WLinstaller to get the .msi on my machine. The installer for Windows Liver Writer Beta 3 can be found here, along with those for the other products in the Live Suite.

Almost makes you wonder if the Live Team messed up the installer, or intentionally excluded x64 to promote SkyDrive.

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Sunday, September 30, 2007 3:33:13 PM (W. Europe Daylight Time, UTC+02:00)
# Saturday, September 22, 2007

No big deal really and since I already toke some time to work on my server, I figured I might do the other outstanding chore too; upgrading the blog-engine to dasBlog 2.0.7226. I did a test upgrade on my (virtual) dev-server first. No real problems, just the an overzealous DasBlogUpgrader.exe (but you can prevent that by taking a good look at the badWords in DasBlogUpgrader.exe.config and removing the appropriate words from that list (like where free set out to delete some referrer-url’s that were okay)). Upgrade instructions are pretty straight forward, but when hitting the uploading section you need to run the difference check on the /config/site.config file too (and not just on the /web.config). ASP.NET issues were not applicable in my case, as I was already running dasBlog 1.9.7067 on ASP.NET 2.0.

One other nice feature, dasBlog now comes with a Windows Live Writer manifest file (wlwmanifest.xml), giving you some admin shortcuts from Live Writer (or take a look before you try).

Speaking of WLW, it seems a new version (Beta 3) was released at September 5th ... save this post as draft ... download new version ... well forget just about that for a moment ... I get the message stating no Windows Live products can be installed on my OS (x64 Windows Vista).

Also Microsoft's web servers are trying to be smart again about the version you should download; Dutch version: http://g.live-int.com/1rebeta/nl-nl/WLInstaller.exe , US-English version: http://g.live-int.com/1rebeta/en-us/WLInstaller.exe. So just download the language-culture you want by substituting the path... now just waiting for the confirmation of the problem on x64 (which you can find here, semi-official).

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Saturday, September 22, 2007 8:53:39 PM (W. Europe Daylight Time, UTC+02:00)

Okay, I had the occasional SPAM message hitting my inbox, like every 1 out of 10 e-mails. But over the last couple of weeks that ratio seemed to flip. I had to do something in order to take back control; take some time for it now in order to save some time in the future. Since I don't believe in filtering in the inbox (or server based filtering of content for that matter), it had to be a solution at the receiving end of the server. Also, blocking at the receiver alerts the sender of a false positive that the e-mail they send will not be read (non-delivery error) which on the long run is far less intrusive to communication than silently dropping the false positive.

Building on past experience as systems administrator (I'm talking about the year 2003 now), we had about 97% of all incoming mails being either SPAM or addressed to no-existing mailboxes. For e-mail security we used MIMEsweeper, but it first received the mail (receiver service) and then processed it according its policies (security service). This way of working was both overloading the server and producing silent false positives (not many, but still). In order to fight SPAM more efficiently and be able to better spot false positives, we needed a solution capable of denying access to the server... and we found just the product to do that: Open Relay Filter by Vamsoft. This enabled to both block blacklisted servers at the door and reject mail for non-existing recipients, and instead of having to add another mail-gateway to support the overloaded server, utilization levels of the mail-gateway dropped to an acceptable level.

About 2 years back, Vamsoft invited MCT's to sign up for ORF for free, I jumped on the offer ;-) and today that offer really helped me out!!! Installation and configuration on my Small Business Server just toke a few minutes (about 25% of time compared to blogging about it).

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SBS
Saturday, September 22, 2007 3:36:36 PM (W. Europe Daylight Time, UTC+02:00)
# Wednesday, September 12, 2007

The IDENTITY property on a column in SQL Server allows to easily create a new number for each row added (INSERT). As a side effect, the column with the IDENTITY property also shows the natural order of records... until something is forgotten and is INSERTed at a later stage. The natural order of things is now disturbed (or has become fragmented, if you like).

CREATE TABLE OrderOfThings_1(
   Ident int IDENTITY(1,1) NOT NULL,
   OrderedSteps varchar(50) NOT NULL)
GO
INSERT OrderOfThings_1 (OrderedSteps) VALUES ('The first step.')
INSERT OrderOfThings_1 (OrderedSteps) VALUES ('The second step.')
INSERT OrderOfThings_1 (OrderedSteps) VALUES ('The fourth step.') -- Notice the forgotten third step.
INSERT OrderOfThings_1 (OrderedSteps) VALUES ('The fifth step.')
GO
SELECT * FROM OrderOfThings_1 ORDER BY Ident
GO
INSERT OrderOfThings_1 (OrderedSteps) VALUES ('The third step.') -- The forgotten third step is added.
GO
SELECT * FROM OrderOfThings_1 ORDER BY Ident
GO
Ident OrderedSteps   Ident OrderedSteps
1 The first step.   1 The first step.
2 The second step.   2 The second step.
3 The fourth step.   3 The fourth step.
4 The fifth step.   4 The fifth step.
      5 The third step.

Naturally we could have anticipated this scenario and set IDENTITY(10,10). But still if the thid step is to be inserted in natural order, this can only be done with significantly more effort. It requires the use of SET IDENTIY_INSERT dbo.OrderOfThings_1 ON, after which the third step can be INSERTed "in order". As the front-end application likely isn't coded for this scenario, it will require the intervention of a dba.

So it would be nice to be able to specify the natural order if needed only, and the best thing in SQL Server to just allow that is the DEFAULT. But the DEFAULT is quite limited; it can neither hold references to columns in the table nor make use of user-defined functions. So any flexibility should come from system functions, literals and operations. By using the IDENTITY property on one column and deriving the natural order from the IDENTITY with a DEFAULT based on IDENT_CURRENT, a flexible and transparent solution is available;

CREATE TABLE OrderOfThings_2(
   Ident int IDENTITY(1,1) NOT NULL,
   OrderOfSteps bigint NOT NULL
     CONSTRAINT df_OveridebleIdentity
       DEFAULT (IDENT_CURRENT('OrderOfThings_2') * 10),
   OrderedSteps varchar(50) NOT NULL)
GO
INSERT OrderOfThings_2 (OrderedSteps) VALUES ('The first step.')
INSERT OrderOfThings_2 (OrderedSteps) VALUES ('The second step.')
INSERT OrderOfThings_2 (OrderedSteps) VALUES ('The fourth step.') -- Notice the forgotten third step.
INSERT OrderOfThings_2 (OrderedSteps) VALUES ('The fifth step.')
GO
SELECT * FROM OrderOfThings_2 ORDER BY Ident
GO
INSERT OrderOfThings_2 (OrderedSteps, OrderOfSteps) VALUES ('The third step.', 25) -- The forgotten third step is added.
GO
SELECT * FROM OrderOfThings_2 ORDER BY OrderOfSteps
GO
Ident OrderOfSteps OrderedSteps   Ident OrderOfSteps OrderedSteps
1 10 The first step.   1 10 The first step.
2 20 The second step.   2 20 The second step.
3 30 The fourth step.   3 25 The third step.
4 40 The fifth step.   4 30 The fourth step.
        5 40 The fifth step.

Note that the OrderOfSteps column is based on bigint, which can hold any int multiplied by 10.

Wednesday, September 12, 2007 7:05:57 PM (W. Europe Daylight Time, UTC+02:00)