Misunderstanding of how Null works is the cause of a great number of errors in SQL code, both in ISO standard SQL statements and in the specific SQL dialects supported by real-world database management systems. These mistakes are usually the result of confusion between Null and either 0 (zero) or an empty string (a string value with a length of zero, represented in SQL as codice_95). Null is defined by the SQL standard as different from both an empty string and the numerical value codice_96, however. While Null indicates the absence of any value, the empty string and numerical zero both represent actual values.