FROM bang
[WHERE dieukien];
Parameters :
Note :
Take a look and explore some examples of AVG functions in SQL Server.
Suppose, we have the following data table:
Example 1: Calculate the average number of posts of the website Quantrimang
SELECT AVG(Sobai) AS "So bai trung binh"
FROM Quantrimang
WHERE Sobai > 100;
Result: So bai trung binh 128.2
In this example we calculate the average value for all the values in the data to be calculated, so the average result is calculated as follows, taking the sum of the Sobai column then dividing by the total number of lines with other data. value greater than 100.
Example 2: Use DISTINCT
SELECT AVG(DISTINCT Sobai) AS "So bai trung binh"
FROM Quantrimang
WHERE Sobai > 100;
Result: So bai trung binh 135
This example uses the keyword DISTINCT , so the repeated values are counted only once. In the given data table, the value '101' appears twice, but is counted only once, so the total number of calculated lines will be 4, the average result is calculated as follows:
(152 + 101 + 122 + 165)/4 = 135
Example 3: Calculate the average value according to the specified column of the selected row
To calculate the average value according to the specified column of the selected rows, we use the GROUP BY clause.
The following example calculates the average of all records related to a large category and you will do the following:
SELECT Chuyenmuclon, AVG(Sobai) AS "So bai trung binh"
FROM Quantrimang
GROUP BY Chuyenmuclon;
Result:
Chuyenmuclon So bai trung binh
Laptrinh 108
Mang xa hoi 158.5
Trinh duyet web 94
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