Friday, June 25, 2010

SQL optimization

Restrict the queries result set by using the WHERE clause.
This can results in good performance benefits, because SQL Server will return to client only particular rows, not all rows from the table(s). This can reduce network traffic and boost the overall performance of the query.

Restrict the queries result set by returning only the particular columns from the table, not all table's columns.
This can results in good performance benefits, because SQL Server will return to client only particular columns, not all table's columns. This can reduce network traffic and boost the overall performance of the query.

Use views and stored procedures instead of heavy-duty queries.
This can reduce network traffic, because your client will send to server only stored procedure or view name (perhaps with some parameters) instead of large heavy-duty queries text. This can be used to facilitate permission management also, because you can restrict user access to table columns they should not see.

Avoid using SQL Server cursors, whenever possible.
SQL Server cursors can result in some performance degradation in comparison with select statements. Try to use correlated subquery or derived tables, if you need to perform row-by-row operations.

Use alternative way instead of SELECT COUNT(*) statement.
Because SELECT COUNT(*) statement make a full table scan to return the total table's row count, it can take very many time for the large table. There is another way to determine the total row count in a table. You can use sysindexes system table, in this case. There is ROWS column in the sysindexes table. This column contains the total row count for each table in your database. So, you can use the following select statement instead of SELECT COUNT(*): SELECT rows FROM sysindexes WHERE id = OBJECT_ID('table_name') AND indid < 2 So, you can improve the speed of such queries in several times.

Use constraints instead of triggers, whenever possible.
Constraints are much more efficient than triggers and can boost performance. So, you should use constraints instead of triggers, whenever possible.

Use table variables instead of temporary tables.
Table variables require less locking and logging resources than temporary tables, so table variables should be used whenever possible. The table variables are available in SQL Server 2000 only.

Avoid the HAVING clause, whenever possible.
The HAVING clause is used to restrict the result set returned by the GROUP BY clause. When you use GROUP BY with the HAVING clause, the GROUP BY clause divides the rows into sets of grouped rows and aggregates their values, and then the HAVING clause eliminates undesired aggregated groups. In many cases, you can write your select statement so, that it will contain only WHERE and GROUP BY clauses without HAVING clause. This can improve the performance of your query.

Avoid using the DISTINCT clause, whenever possible.
Because using the DISTINCT clause will result in some performance degradation, you should use this clause only when it is necessary.

Include SET NOCOUNT ON statement into your stored procedures to stop the message indicating the number of rows affected by a T-SQL statement
This can reduce network traffic, because your client will not receive the message indicating the number of rows affected by a T-SQL statement.
Use the select statements with TOP keyword or the SET ROWCOUNT statement, if you need to return only the first n rows.
This can improve performance of your queries, because the smaller result set will be returned. This can also reduce the traffic between the server and the clients.

Use the FAST number_rows table hint if you need to quickly return 'number_rows' rows.
You can quickly get the n rows and can work with them, when the query continues execution and produces its full result set.

Use UNION ALL statement instead of UNION, whenever possible.
The UNION ALL statement is much faster than UNION, because UNION ALL statement does not look for duplicate rows, and UNION statement does look for duplicate rows, whether or not they exist.

Do not use optimizer hints in your queries.
Because SQL Server query optimizer is very clever, it is very unlikely that you can optimize your query by using optimizer hints, more often, this will hurt performance.

Thursday, June 10, 2010

Microsoft Pattern & Practices

http://msdn.microsoft.com/hi-in/practices/default%28en-us%29.aspx

Wednesday, June 9, 2010

Microsoft Foundation Class Library

Microsoft Foundation Class Library

The Microsoft Foundation Class (MFC) Library is a collection of class es (generalized definitions used in object-oriented programming ) that can be used in building application program s. The classes in the MFC Library are written in the C++ programming language. The MFC Library saves a programmer time by providing code that has already been written. It also provides an overall framework for developing the application program.

There are MFC Library classes for all graphical user interface elements (windows, frames, menus, tool bars, status bars, and so forth), for building interfaces to database s, for handling events such as messages from other applications, for handling keyboard and mouse input, and for creating ActiveX control s.

Wednesday, June 2, 2010

ASP.NET Authentications

Form Authentication reference:-
http://support.microsoft.com/kb/308157

Windows Authentication Reference:-
http://msdn.microsoft.com/en-us/library/ff647405.aspx