Is ‘Is Distinct from’ Is a real mysql operator?

SELECT * FROM inw WHERE id IS DISTINCT FROM 4;

mysql> SELECT * FROM inw WHERE id is null OR id <> 4;
+------+
| id |
+----- -+
| NULL |
| NULL |
| 3 |
+------+

SELECT * 
FROM inw 
WHERE not id <=> 4;

In a book, I saw this syntax:

SELECT * FROM inw WHERE id IS DISTINCT FROM 4;

But I received an error:

ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near’DISTINCT FROM 4’at line 1

It is another option:

mysql> SELECT * FROM inw WHERE id is null OR id <> 4;
+------+
| id |
+------+
| NULL |
| NULL |
| 3 |
+------+

‘ Is IS DISTINCT FROM’ a real MySQL operator?

Different from the definition defined in the SQL:2003 standard, it is a null safe operator that compares two values.

MySQL supports the “null safe equals” operator: <=>. If you negate, you will get the same behavior. (< =>corresponds to not the same)

SELECT * < br />FROM inw 
WHERE not id <=> 4;

SQLFiddle: http://sqlfiddle.com/#!2/0abf2a/3

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