Help to understand .Net

PRIMARY KEY AND UNIQUE KEY are similar except it has different functions. Primary key makes the table row unique (i.e, there cannot be 2 row with the exact same key). You can only have 1 primary key in a database table. Unique key makes the table column in a table row unique (i.e., no 2 table row may have the same exact value). You can have more than 1 unique key table column (unlike primary key which means only 1 table column in the table is unique). Primary Key Unique Key It will not accept null values One and only one Null values are accepted. There will be only one primary key in a table More than one unique key will be there in a table. Clustered index is created in Primary key Non-Clustered index is created in unique key. Primary key allows each row in a table to be uniquely identified and ensures that no duplicate rows exist. Unique key constraint is used to prevent the duplication of key values

It is sometimes useful to display the number of visits a page on a Web site has experienced using a counter that's displayed as part of the page's content. This is a very simple hit counter / page counter to see how many people have visited a web page if you want to show it on a web page. This is a simple using the Application in ASP.NET Application Object The Application object is used to store and access variables from any page, just like the Session object. The difference is that ALL users share ONE Application object (with Sessions there is ONE Session object for EACH user). The Application object holds information that will be used by many pages in the application (like database connection information). The information can be accessed from any page. The information can also be changed in one place, and the changes will automatically be reflected on all pages. Global.aspx The global.asax file is used to add application level logic & processing.