This post can help with the following : Provide an introduction to MapReduce design patterns Explain MapReduce Design Pattern concepts Here are the categories of MapReduce design patterns : 1) Summarization pattern 2) Filtering pattern 3) Data Organization pattern 4) Join pattern 5) Meta pattern 6) Input Output pattern Here is an introduction …
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Cursor is a pointer to private SQL area to do a specific operation. There are 2 types of Cursors – Implicit Cursor – Explicit Cursor Implicit Cursor: This type of Cursor is created by Oracle automatically when a SQL or DML is executed. Explicit Cursor: This is explicitly created and managed by the user.It …
Continue reading Cursors in OracleJoin Join is a SQL retrieves data from more than one table,views etc The join queries will have a condition in FROM or WHERE Clause. The join condition compares 2 columns based on condition and retrieve the result. You can’t use LOB in where clause. There are many type of joins – Equi Join …
Continue reading Joins in OracleBelow are the ways to retrieve nth highest salary for Employees Option 1: SELECT MAX(Salary) FROM Employee WHERE Salary NOT IN (SELECT MAX(Salary) FROM Employee ) Option 2: SELECT MAX(Salary) from Employee WHERE Salary <> (select MAX(Salary) from Employee ) Option 3: SELECT * /This is the outer query part */ FROM Employee Emp1 WHERE …
Continue reading nth highest salary in Oracle – Interview questionSYNONYM Synonym is an alternative name for database objects like table,view,sequence,procedure,function, package etc Synonyms provide both data independence and location transparency To create a private synonym in your own schema, you must have the CREATE SYNONYM system privilege. To create a private synonym in another user’s schema, you must have the CREATE ANY SYNONYM system …
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