Hi,
'' or empty string is not a null in mysql. This is true for Oracle !
this simple test lets you understand :
***************** Without NULLs
mysql> create table notnull (t varchar(10) NOT NULL);
Query OK, 0 rows affected (0.14 sec)
mysql> insert into notnull values('test1');
Query OK, 1 row affected (0.01 sec)
mysql> insert into notnull values('');
Query OK, 1 row affected (0.02 sec)
mysql> insert into notnull values(NULL);
ERROR 1048 (23000): Column 't' cannot be null
mysql> select * from notnull;
+-------+
| t |
+-------+
| test1 |
| |
+-------+
2 rows in set (0.02 sec)
mysql> select * from notnull where isnull(t);
Empty set (0.02 sec)
***************** With NULLs
mysql> create table isnulle(a varchar(10));
Query OK, 0 rows affected (0.08 sec)
mysql> insert into isnulle values(NULL);
Query OK, 1 row affected (0.03 sec)
mysql> select * from isnulle where isnull(a);
+------+
| a |
+------+
| NULL |
+------+
1 row in set (0.00 sec)
Hope that helps.
Mathias
Selon Ashok Kumar <[EMAIL PROTECTED]>:
> Hi friends,
> I'm having one doubt on "NOT NULL" specification for
> the table field properties. That is i have created on
> table-mine which contains name(Not Null) and pwd(Not
> Null). Now I intended to execute the following query.
>
> "insert into mine values('','')"
>
> This means that i'm trying to insert the null fields
> to the table. but this query is successfully executed
> and 1 row is inserted into table with empty values.
> why it's happening and how can i resolve this problem.
>
> Pls give me suggestions regarding this.
>
> Thanks and Regards,
> Ashok Kumar.P.S
>
>
>
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