Can Multiple Columns Be Used in GROUP BY

Q

Can Multiple Columns Be Used in GROUP BY? - Oracle DBA FAQ - Understanding SQL SELECT Query Statements

✍: FYIcenter.com

A

You can use multiple columns in the GROUP BY clause as shown in the following example. It returns how many employees are having the same salary in each department:

SQL> SELECT department_id, salary, count(*) 
  2  FROM employees GROUP BY department_id,
  3  salary HAVING count(*) > 1;
DEPARTMENT_ID     SALARY   COUNT(*)
------------- ---------- ----------
           90      17000          2
           50       3200          4
           50       2200          2
           50       3600          2
           80      10500          2
           80       9000          2
           50       2700          2
......

2007-04-20, 5327👍, 0💬

How To Define and Use Table Alias Names
How To Define and Use Table Alias Names? - Oracle DBA FAQ - Understanding SQL SELECT Query Statements When column names need to be prefixed with table names, you can define table alias name and use them to prefix column names as shown in the following select statement: SQL> SELECT e.first_name, e.la... 2007-04-19, 5872👍, 0💬

How To Write a Query with a Left Outer Join
How To Write a Query with a Left Outer Join? - Oracle DBA FAQ - Understanding SQL SELECT Query Statements If you want to query from two tables with a left outer join, you can use the LEFT OUTER JOIN ... ON clause in the FROM clause. The following query returns output with a left outer join from two ... 2007-04-19, 5592👍, 0💬

How To Join Two Tables in a Single Query
How To Join Two Tables in a Single Query? - Oracle DBA FAQ - Understanding SQL SELECT Query Statements Two tables can be joined together in a query in 4 ways: Inner Join: Returns only rows from both tables that satisfy the join condition. Left Outer Join: Returns rows from both tables that satisfy t... 2007-04-20, 5477👍, 0💬

Can Group Functions Be Mixed with Non-group Selection Fields
Can Group Functions Be Mixed with Non-group Selection Fields? - Oracle DBA FAQ - Understanding SQL SELECT Query Statements If a group function is used in the SELECT clause, all other selection fields must be group level fields. Non-group fields can not be mixed with group fields in the SELECT clause... 2007-04-20, 5406👍, 0💬

How To Use Group Functions in the SELECT Clause
How To Use Group Functions in the SELECT Clause? - Oracle DBA FAQ - Understanding SQL SELECT Query Statements If group functions are used in the SELECT clause, they will be used on the rows that meet the query selection criteria, the output of group functions will be returned as output of the query.... 2007-04-20, 5334👍, 0💬

Can Multiple Columns Be Used in GROUP BY
Can Multiple Columns Be Used in GROUP BY? - Oracle DBA FAQ - Understanding SQL SELECT Query Statements You can use multiple columns in the GROUP BY clause as shown in the following example. It returns how many employees are having the same salary in each department: SQL> SELECT department_id, salary... 2007-04-20, 5328👍, 0💬

How To Write a Query with an Inner Join
How To Write a Query with an Inner Join? - Oracle DBA FAQ - Understanding SQL SELECT Query Statements If you want to query from two tables with an inner join, you can use the INNER JOIN ... ON clause in the FROM clause. The following query returns output with an inner join from two tables: employees... 2007-04-19, 5281👍, 0💬

How To Count Duplicated Values in a Column
How To Count Duplicated Values in a Column? - Oracle DBA FAQ - Understanding SQL SELECT Query Statements If you have a column with duplicated values, and you want to know what are those duplicated values are and how many duplicates are there for each of those values, you can use the GROUP BY ... HAV... 2007-04-20, 5137👍, 0💬

How To Apply Filtering Criteria at Group Level
How To Apply Filtering Criteria at Group Level? - Oracle DBA FAQ - Understanding SQL SELECT Query Statements If you want to return only specific groups from the query, you can apply filtering criteria at the group level by using the HAVING clause inside the GROUP BY clause. The following script give... 2007-04-20, 5067👍, 0💬

All rights in the contents of this web site are reserved by the individual author. fyicenter.com does not guarantee the truthfulness, accuracy, or reliability of any contents.