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How to use SQL GROUP BY Clause?

Hi guys

I want to know that how to use SQL GROUP BY Clause?


Last updated:10/17/2016 11:33:09 PM

2 Answers

Abhishek Srivasatava
Abhishek Srivasatava

Hi Allen,

Group by always used when there is any aggregate function like count.

Here is a small program to understand the logic for group by

SELECT empl_stat_cd , prsn_intn_id , count (prsn_intn_id)
GROUP BY empl_stat_cd , prsn_intn_id

It will check that how many times prsn_intn_id is present in the column for the group of empl_stat_cd , prsn_intn_id.

After writing group we need to write the entire column name whatever we need to fetch from select statement.

If we don’t use group by then it is not possible to count error will come. In the above example if we put two column under select then count function accordingly.

Last updated:10/17/2016 11:33:09 PM
Hubert Jason
Hubert Jason

The GROUP BY clause will gather all of the rows together that contain data in the specified column(s) and will allow aggregate functions to be performed on the one or more columns. 

GROUP BY clause syntax:
SELECT column1, 
FROM "list-of-tables"
GROUP BY "column-list";
Let's say you would like to retrieve a list of the highest paid salaries in each dept:
SELECT max(salary), dept
FROM employee 
GROUP BY dept;
This statement will select the maximum salary for the people in each unique department. Basically, the salary for the person who makes the most in each department will be displayed. Their, salary and their department will be returned

Last updated:10/17/2016 11:33:09 PM