Question : how  to sum top 3 columns values in mysql query?

Hi,

I am using MYSQL database. I want to sum top three class hours using mysql query?


SELECT SUM(CLASS_HOURS) AS TOTALHOURS FROM `tbl_class` ORDER BY CLASS_HOURS DESC LIMIT 3


When i execute this query i am getting total hours as TOTALHOURS=15,  It sums all. It should sum only top three class_hours and desired out put is 12

Can any one help me how to resolve this?

Code Snippet:

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Class_hours Sub_Name 2 English 1 Chemistry 3 Adv. Mathematics 5 General Science 4 Basic Management SELECT SUM(CLASS_HOURS) AS TOTALHOURS FROM `tbl_class` ORDER BY CLASS_HOURS DESC LIMIT 3

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Answer : how  to sum top 3 columns values in mysql query?

SELECT SUM(CLASS_HOURS) AS TOTALHOURS FROM (
   SELECT CLASS_HOURS FROM `tbl_class` ORDER BY CLASS_HOURS DESC LIMIT 3
) AS T