Oracle DBA Interview Question and Answers

21. Explain materialized views?
 
  • Materialized views are called snapshot.
  • They represent a state of data at a specific point to time.
  • These are generally used in warehouse application to avoid commonly used data analysis by storing analyzed data. Unlike normal views, they actually store data and need to be refreshed.
 
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22. What is the use of dynamic SQL?
 
  • Dynamic SQL is an enhanced form of Structured Query Language (SQL) that is used to build SQL statement at runtime.
  • It is used when you do not know all parts of the SQL while writing the SQL.
 
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23. What is a cursor?
  Cursor is a handle or pointer to memory context area allocated for the execution of SQL statement.
 
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24. What is Analytical function?
 
  • Analytical functions are used to perform data analysis for different subsets of a data set.
  • This is achieved through partition clause.
  • There are different types of analytical functions available in Oracle, which are given as follows.
  • Ranking functions, such as rank, dense_rank, row_number, ntile, percent_rank and cume_dist.
  • Windows functions, such as sum, max and avg.
 
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