COUNT(*) function
877644Jul 25 2011 — edited Jul 29 2011When i give
SELECT
COUNT(Salary)
FROM Employees;
--It counts number of fields in Salary column and returns value ignoring NULL fields.
But when we give COUNT(*), COUNT function is going to count which column..???
Likewise, when i give COUNT(constant), what is it doing ??????
And it is said that COUNT(constant) takes less time than COUNT(*) even though they return same output, Why is it so ????????
Can Anyone tell me what is internally happening during execution of this function.??