Hi folks,


mysql version
Ver 14.12 Distrib 5.0.32


I ran following command creating a table:-

mysql> CREATE TABLE `tblPerdition` (
     -> `user` varchar(128),
     -> `servername` varchar(255) default '',
     -> `port` varchar(8) NULL default 'NULL', 
    -> PRIMARY KEY (`user`) 
    -> ); 
Query OK, 0 rows affected (0.00 sec)

mysql> DESCRIBE tblPerdition;
+------------+--------------+------+-----+---------+-------+
| Field      | Type         | Null | Key | Default | Extra |
+------------+--------------+------+-----+---------+-------+
| user       | varchar(128) | NO   | PRI |         |       |
| servername | varchar(255) | YES  |     |         |       |
| port       | varchar(8)   | YES  |     | NULL    |       |
+------------+--------------+------+-----+---------+-------+
3 rows in set (0.00 sec)

I can't figure out how to made Null columns of 'user' blank (without NO)
and 'servername' blank (without YES)


Please help. TIA


B.R.
satimis

user is a primary key so cannot allow NULL entries

NOT NULL is the parameter to NOT allow NULL fields

Originally Posted by chrishirst

user is a primary key so cannot allow NULL entries

NOT NULL is the parameter to NOT allow NULL fields

Hi chrishirst,


Thanks for your advice.


Is "NO" on the Null field similar to blank?


Edit:

I was following this thread re MySQL;
http://www.vergenet.net/linux/perdit...tiondb.5.shtml

to set up this table.


B.R.
satimis

A "NO" in the NULL descriptor column means that the entry for that column in any row MUST HAVE A VALUE it is not allowed to be NULL.
A "YES" in the column indicates that is can be NULL

and no, NULL is not similar to blank, as blank may mean that the column contains a zero length string (""). NULL is nothing.

Originally Posted by chrishirst

A "NO" in the NULL descriptor column means that the entry for that column in any row MUST HAVE A VALUE it is not allowed to be NULL.
A "YES" in the column indicates that is can be NULL

and no, NULL is not similar to blank, as blank may mean that the column contains a zero length string (""). NULL is nothing.

Hi chrishirst,


Please advise how to make "Null" blank. Thanks


Tried follow without success;

mysql> CREATE TABLE `tblPerdition` ( 
     -> `user` varchar(128) null '' primary key,
     -> `servername` varchar(255) null '',
     -> `port` varchar(8)     -> );
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 ''' primary key,
`servername` varchar(255) null '',
`port` varchar(8)
)' at line 2

B.R.
satimis

`user` varchar(128) null '' primary key,

1/ You cannot allow NULL entries in a primary key

from http://dev.mysql.com/doc/refman/5.0/...ate-table.html

A PRIMARY KEY is a unique index where all key columns must be defined as NOT NULL. If they are not explicitly declared as NOT NULL, MySQL declares them so implicitly (and silently). A table can have only one PRIMARY KEY. If you do not have a PRIMARY KEY and an application asks for the PRIMARY KEY in your tables, MySQL returns the first UNIQUE index that has no NULL columns as the PRIMARY KEY.

Please advise how to make "Null" blank. Thanks

You can't, NULL is not blank.
NULL is a special case and is the absence of anything

the error is caused by your code missing out the DEFAULT column descriptor

servername` varchar(255) null DEFAULT '',

Including the "NULL" when creating the table is not necessary. Unless you specify "NOT NULL", the column will allow NULL entries on non key fields.

Originally Posted by chrishirst

`user` varchar(128) null '' primary key,

1/ You cannot allow NULL entries in a primary key

from http://dev.mysql.com/doc/refman/5.0/...ate-table.html


You can't, NULL is not blank.
NULL is a special case and is the absence of anything

the error is caused by your code missing out the DEFAULT column descriptor

servername` varchar(255) null DEFAULT '',

Including the "NULL" when creating the table is not necessary. Unless you specify "NOT NULL", the column will allow NULL entries on non key fields.

Hi crishirst,


Thanks for your advice.


Re-run following command;

mysql> CREATE TABLE `tblPerdition` (
     -> `user` varchar(128) primary key,
     -> `servername` varchar(255) not null,
     -> `port` varchar(8)
     -> ); Query OK, 0 rows affected (0.00 sec)

mysql> DESCRIBE tblPerdition;
+------------+--------------+------+-----+---------+-------+
| Field      | Type         | Null | Key | Default | Extra |
+------------+--------------+------+-----+---------+-------+
| user       | varchar(128) | NO   | PRI |         |       |
| servername | varchar(255) | NO   |     |         |       |
| port       | varchar(8)   | YES  |     | NULL    |       |
+------------+--------------+------+-----+---------+-------+
3 rows in set (0.00 sec)

I suppose I can't make "Null' blank?


B.R.
satimis

I suppose I can't make "Null' blank?

IF you mean the column descriptor (as shown by "DESCRIBE table") No you can't, it will be "YES" or "NO"

Originally Posted by chrishirst

IF you mean the column descriptor (as shown by "DESCRIBE table") No you can't, it will be "YES" or "NO"

Noted with thanks


satimis