Techie sathya

  Yesterday I when I was looking into the enhancements in SQL server 2005 I discovered the below cool features and thought of sharing with your all. This new features will reduce the amount of coding and drastically improve the performance of complex SQL queries.  Conventionally we generate sequence numbers using complex logic or by using temp tables or table variable with identity columns, but with this new feature “ROW_NUMBER()” will allow developers to generate sequence numbers in a single line of code. Below I have attached an example. ROW_NUMBER()returns the sequence number of a row within a partition of a result set, starting at 1 for the first row in each partition. Syntax: ROW_NUMBER ( ) OVER ( [ <partition_by_clause> ] <order_by_clause> ) Example usage: CREATE TABLE RowNumTest (Name VARCHAR(50), DOB DATETIME, Age AS (DATEDIFF(YEAR,DOB,GETDATE()))) INSERT INTO RowNumTest (Name, DOB) VALUES('Sathya', '1983-11-02') INSERT INTO RowNumTes

                Today when I was looking into the new features of SQL server 2005, I came across a concept of computed columns and thought of sharing with you all. Usually we use computed columns of dataset in application side with adds overhead to the application and potentially reducing the performance of the application. Computed columns in the dataset in the application side can be replaced with computed columns in the SQL server table. A computed column is not a physical column in a table but computed from an expression that uses other columns in the same table. The data’s in the computed columns will not be saved physically in the table unless it is marked as PERSISTED. When a computed column is marked as persisted index can be created on it. For example computed columns could have the definition datediff(year,[DOB],getdate()).  The expression can be a non-computed column name, constant, function, variable and any combination of their connected by one or more operators. The exp