Bug #20154 Empty string in text/varchar columns should not be displayed as NULL

• Submitted: 30 May 2006 20:29
• Modified: 30 May 2006 21:12
• Reporter: Christian Hammers (Silver Quality Contributor) (OCA)
• Status: Duplicate
• Category: MySQL Server
• Severity: S3 (Non-critical)
• Version: 5.0.21
• OS: Linux (Debian GNU/Linux Sid)
• CPU Architecture: Any

[30 May 2006 20:29] Christian Hammers

Description:
As reported as Debian Bug #368663 by Larry Holish <[e-mail]> and confirmed by me:
An empty string ("") in varchar and text columns should not be displayed as NULL it the client
as it does not pass the "is null" test.

bye,

-christian-

How to repeat:
mysql> CREATE TABLE t (a varchar(255) default null,   b text default null);
mysql> INSERT INTO t VALUES ("", "");

mysql> SELECT * FROM t;
+------+------+
| a    | b    |
+------+------+
| NULL | NULL | 
+------+------+
1 row in set (0.00 sec)

Suggested fix:
Display "" instead of NULL.

[30 May 2006 20:31] Christian Hammers

I've just found #20067 which describes the same problem but was reported in the category
"MySQL Query Browser". It should probably reassigned to "Server", too, and merged with this one.

[30 May 2006 21:12] Valeriy Kravchuk

Thank you for a problem report. Looks like a duplicate of bug #19564, already fixed in 5.0.22. Please, check.

mysql> CREATE TABLE t (a varchar(255) default null,   b text default null);
Query OK, 0 rows affected (0.02 sec)

mysql> INSERT INTO t VALUES ("", "");
Query OK, 1 row affected (0.01 sec)

mysql>  SELECT * FROM t;
+------+------+
| a    | b    |
+------+------+
|      |      |
+------+------+
1 row in set (0.01 sec)

mysql> select version();
+------------+
| version()  |
+------------+
| 5.0.23-log |
+------------+
1 row in set (0.01 sec)