# CORR and COVAR_SAMP compliant with SQL:2011

Learn about the changes introduced to ensure that the CORR and COVAR_SAMP built-in aggregate functions (UDAFs) are in compliance with the SQL:2011 standards.

**Before upgrade to CDP**

The CORR and COVAR_SAMP aggregate functions were not in compliance with SQL:2011 standards.
CORR returned 'NaN' for `N*SUM(x*x) = SUM(x)*SUM(x)`

and ```
N*SUM(y*y) =
SUM(y)*SUM(y)
```

. However, the function is expected to return NULL per the standards.

Similarly, COVAR_SAMP returns '0' when the function is applied to a set with a single element. The function is expected to return NULL.

**After upgrade to CDP**

HIVE-16178 fixes the compliance issues and ensures that these functions comply with SQL:2011 standards.