Group By

GROUP BY

Group by clause is used to group the results of a SELECT query based on one or more columns. It is also used with SQL functions to group the result from one or more tables.

Syntax for using Group by in a statement.

SELECT column_name, function(column_name)

FROM table_name 

WHERE condition 

GROUP BY column_name

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Example of Group by in a Statement

Consider the following Emp table.

eid	name	age	salary
401	Anu	22	9000
402	Shane	29	8000
403	Rohan	34	6000
404	Scott	44	9000
405	Tiger	35	8000

Here we want to find name and age of employees grouped by their salaries or in other words, we will be grouping employees based on their salaries, hence, as a result, we will get a data set, with unique salaries listed, along side the first employee's name and age to have that salary. Hope you are getting the point here!

group by is used to group different row of data together based on any one column.

SQL query for the above requirement will be,

SELECT name, age 

FROM Emp GROUP BY salary

Result will be,

name	age
Rohan	34
Shane	29
Anu	22

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Example of Group by in a Statement with WHERE clause

Consider the following Emp table

eid	name	age	salary
401	Anu	22	9000
402	Shane	29	8000
403	Rohan	34	6000
404	Scott	44	9000
405	Tiger	35	8000

SQL query will be,

SELECT name, salary

FROM Emp

WHERE age > 25

GROUP BY salary

Result will be.

name	salary
Rohan	6000
Shane	8000
Scott	9000

You must remember that Group By clause will always come at the end of the SQL query, just like the Order by clause.