Skip to main content

Creating View and Guidelines in SQL Server

Database administrator might want to restrict access of data to different users. They might want some users to be able to access all the columns of a table whereas other users to be able to access only selected columns. The SQL Server allows you to create views to restrict user access to the data. Views also help in simplifying query execution when the query involves retrieving data from multiple tables by applying joins.

A view is a virtual table, which provides access to a subset of columns from one or more tables. It is a query stored as an object in the database, which does not have its own data. A view can derive its data from one or more tables, called the base tables or underlying tables. Depending on the volume of data, you can create a view with or without an index. As a database developer, it is important for you to learn to create and manage views.

Creating Views

A view is a database object that is used to view data from the tables in the database. A view has a structure similar to a table. It does not contain any data, but derives its data from the underlying tables.

Views ensure security of data by restricting access to:

  • Specific rows of a table
  • Specific columns of a table
  • Specific rows and columns of a table
  • Rows fetched by using joins
  • Statistical summary of data in a given table
  • Subsets of another view or a subset of views and tables

Apart from restricting access, views can also be used to create and save queries based on multiple tables. To view data from multiple tables, you can create a query that includes various joins. If you need to frequently execute this query, you can create a view that executes this query. You can access data from this view every time you need to execute the query.

You can create a view by using the CREATE VIEW statement. The syntax of the CREATE VIEW statement is:

CREATE VIEW view_name
[ (column_name [, column_name]…)]
AS select_statement [WITH CHECK OPTION]


  • View_name specifies the name of the view.
  • Column_name specifies the name of the column(s) to be used in a view.
  • WITH ENCRYPTION specifies that the text of the view will be encrypted in the syscomments view.
  • SCHEMABINDING binds the view to the schema of the underlying table or tables.
  • AS specifies the action to be performed by the view.
  • Select_statement specifies the SELECT statement that defines a view. The view may use the data contained in other views and tables.
  • WITH CHECK OPTION forces the data modification statements to meet the criteria given in the SELECT statement defining the view. The data is visible through the view after the modifications have been made permanent.

Guidelines for creating views

While creating views, you should consider the following guidelines:

  • The name of a view must follow the rules for identifiers and must not be the same as that of the table on which it is based.
  • A view can be created only if there is a SELECT permission on its base table.
  • A view cannot derive its data from temporary tables.
  • In a view, ORDER BY cannot be used in the SELECT statement.

For example, to provide access only to the employee ID, marital status, and department ID for all the employees you can create the following view:

CREATE VIEW HumanResources.vwEmployeeDepData
SELECT e.EmployeeID, MaritalStatus, DepartmentID
FROM HumanResources.Employee e JOIN
HumanResources.EmployeeDepartmentHistory d
ON e.EmployeeID = d.EmployeeID

The preceding code crates the vwEmployeeDepData view containing selected columns from the Employee and EmployeeDepartmentHistory tables.


Popular posts from this blog

difference between structure and union in C Language

In c language article we will see the difference between union and structure. Both are the user define datatype in c language. See the table which is mentioned below: ASP.NET Video Tutorial Series Structure Union1.The keywordstruct is used to define a structure 1. The keyword union is used to define a union. 2. When a variable is associated with a structure, the compiler allocates the memory for each member. The size of structure is greater than or equal to the sum ofsizes of its members. The smaller members may end with unused slack bytes. 2. When a variable is associated with a union, thecompiler allocates thememory by considering the size of the largest memory. So, size of union is equal to the size of largest member. 3. Each member within a structure is assigned unique storage area of location. 3. Memory allocated is shared by individual members of union. 4. The address of each member will be in ascending order This indicates that memory for each member will start at different offset v…

Difference between Linear search and Binary Search in c language

SQL Video Channel : Download all SQL Video

Binary Search Linear Search Works only on sorted items. such as  1,2,3,4,5,6  etc
Works on sorted as well as unsorted items. 12,4,5,3,2,1 etc Very efficient if the items are sorted Very efficient if the items are less and present in the beginning of the list. such as Suppose your list items are : 12,3,4,5,1 and you want to search 12 number then you get beginning in the list. Works well with arrays and not on linked lists. Works with arrays and linked lists.
Number of comparisons are less More number of comparisons are required if the items are present in the later part of the array or its elements are more.

Memory representation of Linked List Data Structures in C Language

Memory representation of Linked List

             In memory the linked list is stored in scattered cells (locations).The memory for each node is allocated dynamically means as and when required. So the Linked List can increase as per the user wish and the size is not fixed, it can vary.

               Suppose first node of linked list is allocated with an address 1008. Its graphical representation looks like the figure shown below:

      Suppose next node is allocated at an address 506, so the list becomes,

  Suppose next node is allocated with an address with an address 10,s the list become,

The other way to represent the linked list is as shown below:

 In the above representation the data stored in the linked list is “INDIA”, the information part of each node contains one character. The external pointer root points to first node’s address 1005. The link part of the node containing information I contains 1007, the address of next node. The last node …