| | 9 | ''"Although Oracle treats zero-length character strings as nulls, concatenating a zero-length character string with another operand always results in the other operand, so null can result only from the concatenation of two null strings. However, this may not continue to be true in future versions of Oracle Database. To concatenate an expression that might be null, use the NVL function to explicitly convert the expression to a zero-length string."'' (see [https://docs.oracle.com/database/121/SQLRF/operators003.htm#SQLRF51158 documentation]). |