Posted by jpluimers on 2014/01/22
A while ago, I came across an interesting post Bad Habits to Kick : Using AS instead of = for column aliases by Aaron Bertrand, a major contributor on SQLblog.com – The SQL Server blog spot on the web.
The last link indicates my problem with this “AS” versus “=”: it is SQL Server specific.
So, if you mainly use SQL Server, then it is OK (or even preferable) to use “=” for aliasing columns in human written SQL as it makes spotting the names used much easier. Read the rest of this entry »
Posted in Access, Database Development, DB2, Development, Firebird, InterBase, MySQL, OracleDB, Paradox, PostgreSQL, SQL, SQL Server, Sybase | Leave a Comment »
Posted by jpluimers on 2014/01/14
Last year, I had a very odd project at a client.
Their monitoring software was quite odd, and there was no time to create/test/implement a module for it doing SQL query performance measurement any better.
The odd software had two ways of looking at queries:
Don’t ask why it was that way, the monitor was hysterically grown.
So below is a small query script that does what the odd monitoring software can do: provide a select with rows indicating the query response time.
What is does is insert into the #sma temporary table a number of records depending on the query duration.
The partition here is 1 record per 125 milliseconds, aiming for four partitions (green, yellow, orange, red) in half a second.
Note the maximum accuracy is about 3.3 milliseconds.
The script is based on these SQL server features:
I might add a try/catch to fake a finally in case the #sma insert fails. Read the rest of this entry »
Posted in Database Development, Development, SQL Server, SQL Server 2000, SQL Server 2005, SQL Server 2008, SQL Server 2008 R2, SQL Server 2012 | Leave a Comment »
Posted by jpluimers on 2014/01/04
David Rodriguez posted a few nice SQL related entries on G+:
–jeroen
via: David Rodriguez – Google+.
Posted in Database Development, Development, SQL, SQL Server | Leave a Comment »
Posted by jpluimers on 2013/12/24
This has bitten me so many times, so I’m glad I found the below question/answers on StackOverflow.
When you perform calculations in SQL Server involving numeric literals, you have to take into account which precision you want your result to be, and CAST/CONVERT the literals accordingly.
The reason is condensed to this statement by Lieven Keersmaekers:
SQL Server uses the smallest possible datatype.
He follows with examples to view the actual representation of a literal/expression using SQL_VARIANT_PROPERTY (which has been there since at least SQL Server 2000).
SELECT SQL_VARIANT_PROPERTY(1.0, 'BaseType') SELECT SQL_VARIANT_PROPERTY(1.0, 'Precision') SELECT SQL_VARIANT_PROPERTY(1.0, 'Scale') SELECT SQL_VARIANT_PROPERTY(1.0, 'TotalBytes')
Posted in Algorithms, Database Development, Development, Floating point handling, Software Development, SQL Server, SQL Server 2000, SQL Server 2005, SQL Server 2008, SQL Server 2008 R2, SQL Server 2012, SQL Server 7 | Leave a Comment »
Posted by jpluimers on 2013/12/04
From my link archive:
Note that for importing decimal/numeric columns, you have two options:
Some more links on this:
–jeroen
Posted in Algorithms, CSV, Database Development, Development, Floating point handling, Software Development, SQL Server, SQL Server 2005, SQL Server 2008, SQL Server 2008 R2, SQL Server 2012 | Leave a Comment »
Posted by jpluimers on 2013/11/29
I just got this error when SQL Server Management Studio 2012 was complaining about the owner of a certain SQL Server 2012 database and tried to copy that message to the clipboard:
This message cannot be copied to the clipboard.
Additional information
Current thread must be set to single thread apartment (STA) mode before OLE calls can be made.
Ensure that your Main function has STAThreadAttribute marked on it. (System.Windows.Forms)
Is there anyone who knows how to workaround this issue in SSMA?
–jeroen
Posted in Database Development, Development, Software Development, SQL Server, SQL Server 2012 | Tagged: SQL Server 2012, SQL Server Management Studio 2012 | Leave a Comment »
Posted by jpluimers on 2013/10/30
I need to do some research to automate the backups and restore sequences of some SQL Servers.
Here are some links and notes to get started:
Posted in Database Development, Development, SQL Server, SQL Server 2000, SQL Server 2005, SQL Server 2008, SQL Server 2008 R2, SQL Server 2012, SQL Server 7 | Leave a Comment »
Posted by jpluimers on 2013/10/24
“there’s nothing so permanent as temporary” can apply to many things, for instance Kitchen and software development (there technical debt is very applicable), the financial top gap measures (which are real debt) of fanfiction. You can apply it to SQL Server as well. The TempDBhas been there since before SQL Server 7, which means it has established a permanent feature for quite some time now.
Your DBA (which might be you) needs to watch the temdb size or space on the separate volume where temdb is stored, or someday the TemDB access patterns will cause havoc.
The most used feature (there are more) in TempDB is temporary tables (often abbreviated to “temp tables”), which – since TemDB got there – has come in three flavours:
The table variables are created and released implicitly. The temporary tables (one of the Special Table Types) can be created either explicitly using a CREATE TABLE, or implicitly using SELECT … INTO. You’d think that temporary tables are indeed temporary. But they are not:
Temporary tables are semi-temporary. Not actually permanent, but not fully temporary either.
All flavours of temporary tables are not being fully deleted when they go out of scope. When they go out ot scope, they will get an implicit/automatic truncate to empty them (so there is no manual TRUNCATE TABLE or DROP TABLE needed). But the table itself lives on including any cached plan information. They can, and often will be reused. And that’s where you should start reading these links:
One more thing: as of SQL Server 2012, the OBJECT_ID associated with temporary tables is negative.
–jeroen
via:
Posted in Database Development, Development, SQL Server, SQL Server 2000, SQL Server 2005, SQL Server 2008, SQL Server 2008 R2, SQL Server 2012, SQL Server 7 | 2 Comments »
Posted by jpluimers on 2013/10/23
Thanks StackOverflow users George Stocker for asking, Örjan Jämte and Sir Crispalot for answering.
Below is the SQL Server 2012 table, in which I added links to the various data types.
I also added two columns with linked references to the types from the C# data types, C# Keywords, Reference Tables for Types (C# Reference) and Data Type Summary (Visual Basic).
One of the things I need to check is against the LINQ SQL-CLR Type Mapping.
It is very important to keep in mind that in SQL, each combination of precision and digits gets you a different decimal type, and all of them are different from the .NET decimal type. See for instance the answers on these questions:
Posted in .NET, .NET 2.0, .NET 3.0, .NET 3.5, .NET 4.0, .NET 4.5, Algorithms, C#, C# 1.0, C# 2.0, C# 3.0, C# 4.0, C# 5.0, Database Development, Development, Floating point handling, Software Development, SQL Server, SQL Server 2005, SQL Server 2008, SQL Server 2008 R2, SQL Server 2012 | Leave a Comment »
Posted by jpluimers on 2013/10/22
I couldn’t find a table with numeric data types in SQL Server 2012 on MSDN, but since they have not changed since SQL Server 2008, I copied the table from Understand the 9 Numeric Data Types in SQL Server 2008, added an entry for bit, and links to the relevant SQL Server 2012 pages at MSDN.
Edit: somehow the WordPress editing system suppressed all the superscripts (for the powers of 2 and 10), so I replaced them with caret signs and powers of 2 and 10 to make it more clear and verified them against Floating point numbers and these Wikipedia pages:
Data Type Range of Values Storage Space
| Data Type | Range of Values | Storage Space |
| tinyint | 0 to 255 | 1 byte |
| smallint | –32,768 to 32,767 | 2 bytes |
| int | –2^31 to 2^31–1 | 4 bytes |
| bigint | –2^63 to 2^63–1 | 8 bytes |
| decimal(p,s) numeric(p,s) |
–10^38+1 to 10^38–1 | 5 to 17 bytes |
| smallmoney | –214,748.3648 to 214,748.3647 | 4 bytes |
| money | –922,337,203,685,477.5808 to 922,337,203,685,477.5807 | 8 bytes |
| real | –3.4*10^38 to –1.18*10^38, 0, and 1.18*10^38 to 3.4*10^38 | 4 bytes |
| float(n) | –1.79*10^308 to –2.23*10^308, 0, and 2.23*10^308 to 1.79*10^308 | 4 bytes or 8 bytes |
| bit | 0 to 1 | 0+ bytes |
Later I found an even more complete table at SQL Server Data Types Reference – ConnectionStrings.com.
–jeroen
via: Understand the 9 Numeric Data Types in SQL Server 2008.
Posted in Algorithms, Database Development, Development, Floating point handling, Software Development, SQL Server, SQL Server 2008, SQL Server 2008 R2, SQL Server 2012 | Leave a Comment »
The Wiert Corner - irregular stream of stuff 