Aggregate
Functions
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MIN
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Returns
the smallest value in a given column
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MAX
|
Returns
the largest value in a given column
|
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SUM
|
Returns
the sum of the numeric values in a given column
|
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AVG
|
Returns
the average value of a given column
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COUNT
|
Returns
the total number of values in a given column
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COUNT(*)
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Returns
the number of rows in a table
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In database management
system an aggregate function is a function where the values of multiple rows are
grouped together as input and on certain criteria to form a single value. Aggregate
functions are used to compute against a numeric column data from SELECT
statement. This mostly summarize the results of a particular column of selected
data.
For example:
SELECT AVG (MARKS) FROM STUDENTS;
This statement will return
a single result which contains the average value of everything returned in the Marks
column from the Students table.
Another example:
SELECT AVG (SALARY) FROM EMPLOYEE WHERE TITLE=’AVP’;
This statement will return
the average salary for all employee whose title is equal to AVP.
Example:
SELECT COUNT (*) FROM
STUDENTS;
This statement returns the total number of students. However
you can also add additional column or distinct values counts.
Example:-
SELECT COUNT (DISTINCT TITLE)
FROM EMPLOYEE;
