SQL Server Interview Question and Answers

31. What is NOT NULL Constraint?
  A NOT NULL constraint enforces that the column will not accept null values. The not null constraints are used to enforce domain integrity, as the check constraints.
32. What is log shipping?
  Log shipping is the process of automating the backup of database and transaction log files on a production SQL server, and then restoring them onto a standby server. Enterprise Editions only supports log shipping. In log shipping the transactional log file from one server is automatically updated into the backup database on the other server.
33. What is Cross Join?
  A cross join that does not have a WHERE clause produces the Cartesian product of the tables involved in the join. The size of a Cartesian product result set is the number of rows in the first table multiplied by the number of rows in the second table.
34. What is Self Join?
  A self join can be of any type, as long as the joined tables are the same. A self join is rather unique in that it involves a relationship with only one table.
35. What is a default constraint?
  A default constraint is a value that SQL Server automatically places in a particular field in a table.

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