SQL Server and MS BI With a Geek Touch

Query to track all the indexes with fragmentation in a database.

SELECT 

OBJECT_NAME(object_id) AS TablelName

,(SELECT name FROM sys.indexes WHERE object_id = a.object_id and index_id = a.index_id) IndexName

,avg_fragmentation_in_percent

FROM sys.dm_db_index_physical_stats(DB_ID(‘<<DatabaseName>>’), NULL, NULL, NULL, NULL) a

WHERE avg_fragmentation_in_percent > 40

AND index_type_desc IN(‘CLUSTERED INDEX’, ‘NONCLUSTERED INDEX’)

ORDER BY avg_fragmentation_in_percent DESC

The <<DatabaseName>> needs to be filled with the database of your choice.

There was a time when we all wished SQL Server supports compound operators just like any other programming languages. Wouldn’t it be nice to have a shorter syntax for assigning the result of an arithmetic operator?  Well, SQL server 2008 introduced Compound operators that allow you to perform several arithmetic operations using an operand along with equal to (=) operand.

 For example:

Declare @var1  int

Set @var1 = 150

Set @var1 += 100

Read more…

SQL server usually selects the best query plan required to execute a T-SQL query. However, there might be cases where the plans selected are not the best. In such situations, you can use the query hints to suggest the best possible plan/method of executing a query. The Query hints can be applied on all operators in a query. These hints apply to SELECT, DELETE, INSERT, UPDATE and MERGE. You can use the Query hints in the OPTION clause after the query.

Few commonly used Query hints with examples are as below.

Read more…

Everyone reading this must have come across these datatypes, but have you ever thought what are the differences and advantages between these two?

The obvious difference that comes to our mind is related to the length. Yes! You are right. The varchar supports variable length and Char supports fixed length. This is the main advantage varchar datatype. for example,  let us consider varchar(10) and char(10) . To store “GEEKEPISODE”, both the datatypes will use the complete length allocated and to store “GEEK”, CHAR datatype will use the complete 10 characters  allocated, but VARCHAR will use only 4.

From the above examples it might seem that VARCHAR is better than CHAR all the time. But remember, CHAR was included as a separate datatype because it has certain advantages over VARCHAR.

VARCHAR uses additional space to store the length of the string stored in it and to mark the end of the string. Whereas, CHAR datatype doesn’t use this additional space.  This certainly is the advantage of CHAR datatype.

Summary:

Read more…

I often create batch files to execute sql scripts ( specially SPs) and then schedule it using SQL agent job/Task Scheduler. In this post , I will show you how to create a batch file with sql commands.

First of all, The command that is used to execute SQL queries from commnd prompt is “SQLCMD“. The general syntax of this command is available in the link. I will go with a simple one as below

sqlcmd –E –S Servername –Q Query -o “Output Path”

C:\Users\geekEpisodes>  sqlcmd -E -S “Local-SRV01″ -Q “Select top 10 * from MyTestDatabase..[ForecastHistory]” -o “C:\New Folder\Output.txt”

All the commands that you execute in the command prompt can be executed from batch/command files. to create a batch file with SQL commands follow the steps below

Read more…

You can use the string functions to manipulate the string values in the result set. String functions are used with both char and nchar data types. The list below contains the set of string functions available in SQL Server 2005.

Read more…

It is often necessary to change the database to single user mode, especially if you are a DBA. A simple example would be to change the collation settings or any DB settings. The single user will allow only one  user ( usually DBA) to access the database. Hence it will be easy to make changes without the worry of deadlocks or any other type of contention for DB and also without affecting the users.

It is very easy to change the database to Single user mode; in fact, it is just an execution of the script away. Use the script below to change the mode.

ALTER  DATABASE <<Database Name>>  SET SINGLE_USER  WITH NO_WAIT

Read more…

Many times , it may be necessary to remove Not Null constraint used for a column in  a table. It is usually necessary to overcome unexpected integrity constraints ( rarely occurs, if designed well) against a table. We can remove the Not Null constaint by using  ALTER TABLE …. ALTER COLUMN … option.

Read more…

Although these functions are not commonly used, these are really powerful in searching a pattern and returning the location of text/ string/ pattern. By understanding the functionality of both the string functions, we will be able to understand the difference as well.

PATINDEX()

The function searches for a pattern in a string / expression and returns the starting position of the first occurrence of the pattern. It works similar to the LIKE operator in any query.

Read more…