Aggregate functions of Oracle Common functions

Aggregation functions

------------------------------------------aggregate function---------------------------------------------

--1:avg (distinct| All)

All means that all values are averaged, and distinct only averages the different values.

SELECT AVG (SAL) from SCOTT. EMP;

SELECT AVG (DISTINCT SAL) from SCOTT. EMP;

--2:max (distinct| All)

The maximum value, all represents the maximum value for all values, distinct represents the maximum value for the different values, the same only once

(plus no query results consistent, I do not know what the use of distinct, unlike the AVG and other aggregation functions)

SELECT MAX (DISTINCT SAL) from SCOTT. EMP;

SELECT MAX (SAL) from SCOTT. Emp

--3:min (distinct| All)

The minimum value, all means the minimum value for all values, distinct represents the minimum value for different values, the same only once

SELECT MIN (SAL) from SCOTT. EMP;

SELECT MIN (DISTINCT SAL) from SCOTT. EMP;

--4:stddev (Distinct|all)

Standard deviation, all means a standard deviation for all values, distinct means only the standard deviation for different values

SELECT STDDEV (SAL) from SCOTT. EMP;

SELECT STDDEV (DISTINCT SAL) from SCOTT. EMP;

--5:variance (distinct| All)

Covariance all means that all values are covariance, distinct means that only different values are evaluated for covariance

SELECT VARIANCE (SAL) from SCOTT. EMP;

SELECT VARIANCE (DISTINCT SAL) from SCOTT. EMP;

--6:sum (distinct| All)

Sum all means summing all values, distinct means summing only different values (the same value is only taken once)

SELECT SUM (SAL) from SCOTT. EMP;

SELECT SUM (DISTINCT SAL) from SCOTT. EMP;

--7:count (distinct| All)

The number of records and data. All records, arrays are counted, distinct only for the different values (the same value is only taken once)

SELECT COUNT (SAL) from SCOTT. EMP;

SELECT COUNT (DISTINCT SAL) from SCOTT. EMP;

----8:median
To find the median number

SELECT MEDIAN (SAL) from SCOTT. EMP;

SELECT MEDIAN (DISTINCT SAL) from SCOTT. EMP; --Error: The DISTINCT option is disabled in this function.

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Aggregate functions of Oracle Common functions