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Oracle Tutorials - Divide Query Output into Groups

By: FYIcenter.com

(Continued from previous topic...)

How To Divide Query Output into Groups?

You can divide query output into multiple groups with the GROUP BY clause. It allows you specify a column as the grouping criteria, so that rows with the same value in the column will be considered as a single group. When the GROUP BY clause is specified, the select statement can only be used to return group level information. The following script gives you a good GROUP BY example:

SQL> SELECT department_id, MIN(salary), MAX(salary), 
  2 AVG(salary) FROM employees GROUP BY department_id;
DEPARTMENT_ID MIN(SALARY) MAX(SALARY) AVG(SALARY)
------------- ----------- ----------- -----------
          100        6900       12000        8600
           30        2500       11000        4150
                     7000        7000        7000
           90       17000       24000  19333.3333
           20        6000       13000        9500
           70       10000       10000       10000
          110        8300       12000       10150
           50        2100        8200  3475.55556
......

(Continued on next topic...)

  1. What Is a SELECT Query Statement?
  2. How To Select All Columns of All Rows from a Table?
  3. How To Select Some Columns from a Table?
  4. How To Select Some Rows from a Table?
  5. How To Sort the Query Output?
  6. Can the Query Output Be Sorted by Multiple Columns?
  7. How To Sort Query Output in Descending Order?
  8. How To Use SELECT Statement to Count the Number of Rows?
  9. Can SELECT Statements Be Used on Views?
  10. How To Filter Out Duplications in Returning Rows?
  11. What Are Group Functions?
  12. How To Use Group Functions in the SELECT Clause?
  13. Can Group Functions Be Mixed with Non-group Selection Fields?
  14. How To Divide Query Output into Groups?
  15. How To Apply Filtering Criteria at Group Level?
  16. How To Count Duplicated Values in a Column?
  17. Can Multiple Columns Be Used in GROUP BY?
  18. Can Group Functions Be Used in the ORDER BY Clause?
  19. How To Join Two Tables in a Single Query?
  20. How To Write a Query with an Inner Join?
  21. How To Define and Use Table Alias Names?
  22. How To Write a Query with a Left Outer Join?
  23. How To Write a Query with a Right Outer Join?
  24. How To Write a Query with a Full Outer Join?
  25. How To Write an Inner Join with the WHERE Clause?
  26. How To Write a Left Outer Join with the WHERE Clause?
  27. How To Name Query Output Columns?
  28. What Is a Subquery?
  29. How To Use Subqueries with the IN Operator?
  30. How To Use Subqueries with the EXISTS Operator?
  31. How To Use Subqueries in the FROM Clause?
  32. How To Count Groups Returned with the GROUP BY Clause?
  33. How To Return Top 5 Rows?

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