21 messages in com.mysql.lists.mysqlRe: Does Null == ""?| From | Sent On | Attachments |
|---|---|---|
| Randy Chrismon | 15 Sep 2003 09:46 | |
| Mark Richards | 15 Sep 2003 10:02 | |
| Bob Hall | 15 Sep 2003 18:02 | |
| Bruce Feist | 15 Sep 2003 18:52 | |
| Dan Nelson | 15 Sep 2003 19:24 | |
| Jon Frisby | 15 Sep 2003 19:29 | |
| Bruce Feist | 15 Sep 2003 19:33 | |
| Bruce Feist | 15 Sep 2003 19:54 | |
| Bob Hall | 15 Sep 2003 20:20 | |
| Bob Hall | 15 Sep 2003 20:24 | |
| Bob Hall | 15 Sep 2003 20:45 | |
| Bob Hall | 15 Sep 2003 21:28 | |
| Jon Frisby | 16 Sep 2003 11:47 | |
| Bruce Feist | 16 Sep 2003 14:39 | |
| Jon Frisby | 16 Sep 2003 14:55 | |
| Bob Hall | 16 Sep 2003 17:31 | |
| Bob Hall | 17 Sep 2003 12:57 | |
| Bruce Feist | 17 Sep 2003 18:57 | |
| Bob Hall | 17 Sep 2003 21:02 | |
| Haydies | 18 Sep 2003 04:43 | |
| Bob Hall | 18 Sep 2003 12:04 |
| Subject: | Re: Does Null == ""? |
|---|---|
| From: | Bob Hall (rjh...@cox.net) |
| Date: | 09/15/2003 06:02:42 PM |
| List: | com.mysql.lists.mysql |
On Mon, Sep 15, 2003 at 12:46:50PM -0400, Randy Chrismon wrote:
an exort from a Lotus Notes database. At some point, the MySQL documentation says that a table with no nullable columns is better/faster than one with. The Lotus Notes database I'm migrating, however, has many fields with no values. I infer from the MySQL documentation that I'm better off doing:
create table my_table(a_field varchar(16) NOT NULL default "", ...)
and exporting my values from Notes as "" rather than using NULL.
No. The meaning of NULL is defined in the SQL specification; it means "not known" or "not applicable". If you have data that is missing because it is not known or not applicable, then use NULL.
A zero-length string has no defined meaning. I've done maintenance on databases that contained zero-length strings, and they were nightmares. I can't think of any reason why you would use a zero-length string in a database.
Bob Hall