An expression is considered valid if it is syntactically correct and all function, operator and column references can be resolved. If an expression is not valid, it cannot be evaluated. This will be indicated in the Sample result field of the Insert Calculated Column dialog as "#Error", (Empty), or similar. When generating a result data table from the expression, errors are converted to null. Wrap the expression with a call to the SN(Arg1, Arg2) function to override this behavior. The SN(Arg1, Arg2) function can be used to substitute null with a certain value, for example, 0.
Empty values are generated whenever a column value from the data table is missing, when a calculation involves an invalid value, or by explicitly writing null in the expression. Results that are null, are displayed as "(Empty)" or simply left blank.
When aggregating within a column, the invalid value will be ignored, whereas row-wise calculations between columns will result in invalid values each time one of the involved columns contains an invalid value.