The aggregate functions are often used with the GROUP BY clause to calculate an aggregate value for each group e.g., the average value by the group or the sum of values in each group. The following ...

-- MySQL's aggregate function is used to perform calculations on multiple values and return the result in a single value like -- the average of all values, the sum of all values, and maximum & minimum ...

So I am trying to write an update statement that uses two factors to determine the new value of the field, one of the factors is an aggregate function (COUNT). I get the error: An aggregate may ...