Average in SQL - sql - sql tutorial - learn sql

• SQL AVG function is used to find out the average of a field in various records.
• To find the average value in an expression using the AVG function.

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Syntax:

• The syntax for the AVG function is,

SELECT AVG (<expression>)
FROM "table_name";

• can be a column name or an arithmetic operation.
• An arithmetic operation can include more than one column, such as ("column1" * "column2").
• It is also possible to have one or more columns in addition to the AVG function in the SELECT statement.
• In those cases, these columns need to be part of the GROUP BY clause as well:

SELECT "column_name1", "column_name2", ... "column_nameN", AVG (<expression>)
FROM "table_name";
GROUP BY "column_name1", "column_name2", ... "column_nameN";

Examples:

• We use the following table for our examples.

Table Store_Information

Store_Name	Sales	Txn_Date
Los Angeles	1500	Jan-05-1999
San Diego	250	Jan-07-1999
Los Angeles	300	Jan-08-1999
Boston	700	Jan-08-1999

Example 1: AVG function on a column

• To find the average sales amount, we type in,

SELECT AVG(Sales) FROM Store_Information;

Result:

AVG(Sales)
687.5

• 687.5 represents the average value of all Sales entries: (1500+250+300+700) / 4.

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Example 2: AVG function on an arithmetic operation

• Assume that sales tax is 10% of the sales amount, we use the following SQL statement to get the average sales tax amount:

SELECT AVG(Sales*0.1) FROM Store_Information;

Result:

AVG(Sales*0.1)
68.75

• SQL will first calculate "Sales*0.1" and then apply the AVG function to the result for the final answer.

Example 3: AVG function with a GROUP BY clause

• To get the average amount of sales for each store, we type in,

SELECT Store_Name, AVG(Sales) FROM Store_Information GROUP BY Store_Name;

Result:

Store_Name	MIN(Sales)
Los Angeles	900
San Diego	250
Boston	700

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SQL AVG Sample Application

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