SQL GROUP Functions
Group functions are built-in SQL functions that operate on
groups of rows and return one value for the entire group. These functions are: COUNT,
MAX, MIN, AVG, SUM, DISTINCT
SQL COUNT (): This function returns the number of rows in the table that
satisfies the condition specified in the WHERE condition. If the WHERE
condition is not specified, then the query returns the total number of rows in
the table.
For Example: If you want the number of employees in a particular
department, the query would be:
SELECT COUNT (*) FROM EmpDetails WHERE dept = 'HR';
If you
want the total number of employees in all the department, the query would take
the form:
SELECT COUNT (*) FROM EmpDetails
SQL DISTINCT(): This function is used to select the distinct rows.
For Example: If you want to select all distinct department names from EmpDetails table, the query would be:
SELECT DISTINCT dept FROM EmpDetails
To get
the count of employees with unique name, the query would be:
SELECT COUNT (DISTINCT name) FROM EmpDetails;
SQL MAX(): This function is used to get the maximum value from a
column.
To get
the maximum salary drawn by an EmpDetails, the query would be:
SELECT MAX (salary) FROM EmpDetails;
SQL MIN(): This function is used to get the minimum value from a
column.
To get
the minimum salary drawn by an EmpDetails, he query would be:
SELECT MIN (salary) FROM EmpDetails;
SQL AVG(): This function is used to get the average value of a
numeric column.
To get
the average salary, the query would be
SELECT AVG (salary) FROM EmpDetails;
SQL SUM(): This function is used to get the sum of a numeric column
To get
the total salary given out to the EmpDetails,
SELECT SUM (salary) FROM EmpDetails;
