Working with NULL Values : Null « Data Type « SQL / MySQL






  1. SQL / MySQL
  2. Data Type
  3. Null

Working with NULL Values

   
/*
mysql> /*
mysql> NULL means a missing unknown value
mysql>      is treated somewhat differently than other values.
mysql> */
mysql> SELECT 1 = NULL, 1 <> NULL, 1 < NULL, 1 > NULL;
+----------+-----------+----------+----------+
| 1 = NULL | 1 <> NULL | 1 < NULL | 1 > NULL |
+----------+-----------+----------+----------+
|     NULL |      NULL |     NULL |     NULL |
+----------+-----------+----------+----------+
1 row in set (0.00 sec)


*/  

/*
NULL means a missing unknown value
     is treated somewhat differently than other values. 
*/

SELECT 1 = NULL, 1 <> NULL, 1 < NULL, 1 > NULL;








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