SQL Server Interview Question and Answers

66. What does NULL mean?
  The value NULL means UNKNOWN; it does not mean (empty string). Assuming ANSI_NULLS are on in your SQL Server database, which they are by default, any comparison to the value NULL will yield the value NULL.
67. What are the Different Types of Normalization?

  • First Normal Form
  • Second Normal Form
  • Third Normal Form
  • Boyce’s Normal Form
  • Fourth Normal Form
  • Fifth Normal Form

68. What are Page Splits?
  Pages are contained in extent. Every extent will have around eight data pages. But all the eight data pages are not created at once; they are created depending on data demand. So when a page becomes full it creates a new page, this process is called as “Page Split”.
69. What is an Identity?
  Identity is a column that automatically generates numeric values.
70. What is a covered index?
  A covered index is a non clustered index that contains all the columns in a query.

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