Oracle Interview Question and Answers

26. Define a view?
  A view is a virtual table which is based on the one or more physical tables and views.
27. What is the difference between a view and a synonym?
  Synonym is just a second name of table used for multiple link of database.View can be created with many tables, and with virtual columns and with conditions.But synonym can be on view.
28. What is the usage of SAVEPOINTS?
  SAVEPOINTS are used to subdivide a transaction into smaller parts. It enables rolling back part of a transaction. Maximum of five save points are allowed.
  A precompiler is a tool that allows programmers to embed SQL statements in high-level source programs like C, C++, COBOL, etc.The precompiler accepts the source program as input, translates the embedded SQL statements into standard Oracle runtime library calls, and generates a modified source program that one can compile, link, and execute in the usual way.
30. When do you use WHERE clause and when do you use HAVING clause?
  The WHERE condition lets you restrict the rows selected to those that satisfy one or more conditions.Use the HAVING clause to restrict the groups of returned rows to those groups for which the specified condition is TRUE.
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