Venkatesan Prabu MCITP,MCAD,MCTS,CCNA. Worked as a ProjectLead(Senior .Net developer,SQL DBA). Now, Managing Director of KAASHIV INFO TECH, Chennai This Blog aims in serving the community in a better way. This blog is read by developers in 159 countries with average of 400 hits per day. Please post your valuable suggestions and hold my hand to serve the community. Lets make a new world with good thoughts and good minds....... This blog serves the SQL server community all over the world.
What is normalization?
Normalization is the basic concept used in designing a database. Its nothing but, an advise given to the database to have minimal repetition of data, highly structured, highly secured, easy to retrieve. In high level definition, the Process of organizing data into tables is referred to as normalization.
What is a stored procedure:
Stored procedures are precompiled T-SQL statements combined to perform a single task of several tasks. Its basically like a Macro so when you invoke the Stored procedure, you actually run a set of statements. As, its precompiled statement, execution of Stored procedure is compatatively high when compared to an ordinary T-SQL statement.
What is the difference between UNION ALL Statement and UNION ?
The main difference between UNION ALL statement and UNION is UNION All statement is much faster than UNION,the reason behind this is that because UNION ALL statement does not look for duplicate rows, but on the other hand UNION statement does look for duplicate rows, whether or not they exist.
Example for Stored Procedure?
They are three kinds of stored procedures,1.System stored procedure – Start with sp_2. User defined stored procedure – SP created by the user.3. Extended stored procedure – SP used to invoke a process in the external systems.Example for system stored proceduresp_helpdb - Database and its propertiessp_who2 – Gives details about the current user connected to your system. sp_renamedb – Enable you to rename your database
What is a trigger?
Triggers are precompiled statements similar to Stored Procedure. It will automatically invoke for a particular operation. Triggers are basically used to implement business rules.
What is a view?
If we have several tables in a db and we want to view only specific columns from specific tables we can go for views. It would also suffice the needs of security some times allowing specfic users to see only specific columns based on the permission that we can configure on the view. Views also reduce the effort that is required for writing queries to access specific columns every time.
What is an Index?
When queries are run against a db, an index on that db basically helps in the way the data is sorted to process the query for faster and data retrievals are much faster when we have an index.
What are the types of indexes available with SQL Server?
There are basically two types of indexes that we use with the SQL ServerClustered -
1. It will format the entire table, inturn physically sort the table.
2. Only one clustered index can be created for a table.
3. Data will be located in the leaf level.
4. By default, primary key will create clustered index on the table.
Non-Clustered Index
1. It wont touch the structure of the table.
2. It forms an index table as reference to the exact data.
3. A reference to the data will be located in the leaf level.
4. For a table, we can create 249 non clustered index.
Happy Learning!!!
Regards,
Venkatesan Prabu .J
Extent Vs Page?
Pages are low level unit to store the exact data in sql server. Basically, the data will be stored in the mdf, ldf, ndf files. Inturn, pages are logical units available in sql server.The size of the page is 8KB.
Eight consecutive pages will form an extent 8 * 8KB = 64KB.
Thus I/O level operation will be happening at pages level.The pages will hold a template information at the start of each page (header of the page).
They are,
1. page number,
2. page type,
3. the amount of free space on the page,
4. the allocation unit ID of the object that owns the page.
Extents will be classifed into two types,
1. Uniform extents
2. Mixed extents
Uniform Extents:It occupied or used by a single object. Inturn, a single object will hold the entire 8 pages.Mixed
Extents:Mulitple objects will use the same extent. SQL Server will allow a max of eight objects to use a shared extent.
Property of SQL Server :Initally if an object is created, sql server will allocate the object to the mixed extent and once if the size reaches 8 pages and more... immediately, a new uniform extent will be provided for that particular object.
Herecomes, our fragmentation and reindexing concepts.
3 comments:
Found the problem.
We need to add the schemaname.FunctionName to execute it.
alter function Venkat_fun2(@a int)
returns int
as begin
RETURN
(select id from venkat where id=@a)
end
select dbo.Venkat_fun2(1)
The above query will work.
Thanks and Regards,
Venkatesan Prabu .J
Hi Venkat
I am T-SQL Developer and am working for past one and half years in SQL. I need to complete certification can you provide me some tips to complete the certifications. It will help for my preparation.
Regards
Amarnath
Try this
create function Venkat_fun2(@a int)
returns int
as begin
RETURN
(select id from venkat where id=@a)
end
GO
select dbo.Venkat_fun2(1)
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