This package adds several user-defined statistics functions
to the MySQL server providing the ability to:

    * calculate the median of any values,
    * calculate the skewness and kurtosis of a distribution of value
    * retrieve the effective length of the longest value in a STRING column,
    * get the longest value from a STRING column,
    * calculate the faculty of a value,
    * calculate linear regression parameters (intercept, slope, correlation
      coefficent) of any values

WWW: http://mysql-udf.sourceforge.net/