Miscellaneous Functions +------+------+----------+ Use of  GROUPING()  is subject to these limitations: •Do not use subquery  GROUP BY  expressions as  GROUPING()  arguments because matching might fail. For example, matching fails for this query: mysql>  SELECT GROUPING((SELECT MAX(name) FROM t1)) FROM t1 GROUP BY (SELECT MAX(name) FROM t1) WITH ROLLUP; ERROR 3580 (HY000): Argument #1 of GROUPING function is not in GROUP BY • GROUP BY  literal expressions should not be used within a  HAVING  clause as  GROUPING() arguments. Due to differences between when the optimizer evaluates  GROUP BY  and  HAVING , matching may succeed but  GROUPING()  evaluation does not produce the expected result. Consider this query: SELECT a AS f1, ’w’ AS f2 FROM t GROUP BY f1, f2 WITH ROLLUP HAVING GROUPING(f2) = 1; GROUPING()  is evaluated earlier for the literal constant expression than for the  HAVING  clause as a whole and returns 0. To check whether a query such as this is affected, use  EXPLAIN  and look for Impossible having  in the  Extra  column. For more information about  WITH ROLLUP  and  GROUPING() , see Section 12.20.2, “GROUP BY Modifiers” . Given the dotted-quad representation of an IPv4 network address as a string, returns an integer that represents the numeric value of the address in network byte order (big endian).  INET_ATON()  returns NULL  if it does not understand its argument. For this example, the return value is calculated as 10×256 $^{3}$ + 0×256 $^{2}$ + 5×256 + 9. INET_ATON()  may or may not return a non- NULL  result for short-form IP addresses (such as  ’127.1’ as a representation of  ’127.0.0.1’ ). Because of this,  INET_ATON() a should not be used for such addresses. • INET_ATON( expr ) mysql>  SELECT INET_ATON(’10.0.5.9’); -> 167773449 • INET_NTOA( expr ) To store values generated by  INET_ATON() , use an  INT UNSIGNED column rather than  INT , which is signed. If you use a signed column, values corresponding to IP addresses for which the first octet is greater than 127 cannot be stored correctly. See Section 11.1.7, “Out-of-Range and Overflow Handling” . Note Given a numeric IPv4 network address in network byte order, returns the dotted-quad string representation of the address as a string in the connection character set.  INET_NTOA()  returns  NULL  if it does not understand its argument. mysql>  SELECT INET_NTOA(167773449); -> ’10.0.5.9’ 2444