[EMAIL PROTECTED] wrote:

i've got a strange problem with concat() function

i have the following data structure:

CREATE TABLE table1 (
  field1 int(11) NOT NULL auto_increment,
  PRIMARY KEY  (field1)
) ENGINE=MyISAM DEFAULT CHARSET=cp1251 AUTO_INCREMENT=3;

CREATE TABLE table2 (
  field2 varchar(255) NOT NULL default ''
) ENGINE=InnoDB DEFAULT CHARSET=cp1251;

INSERT INTO table1 VALUES (1);
INSERT INTO table1 VALUES (2);
INSERT INTO table2 VALUES ('test');

When i try to execute the following query (the query is meaningless -- it is generated just for debug purpose.
the  original  query  where  the  problem  occured  is  too  long  and
complicated)

This is an important point. Do you get the reported error for the simplified query below? If not, it is useless. To find the problem, we must have a query that produces the problem.

SELECT COUNT(DISTINCT field1) as value1,
        CONCAT(field2, '-') as value2
FROM table1,
        table2
GROUP BY value2

With 4.1.11 on Mac OS X 10.3.9, I get

+--------+--------+
| value1 | value2 |
+--------+--------+
|      2 | test-  |
+--------+--------+
1 row in set (0.09 sec)

i get this error:

ERROR 2006 (HY000): MySQL server has gone away
No connection. Trying to reconnect...
Connection id:    6
Current database: test
ERROR 2013 (HY000): Lost connection to MySQL server during query

Does the mysql server actually crash, or are you just losing the connection from your client? Have you checked the error log? Have you checked the manual <http://dev.mysql.com/doc/mysql/en/gone-away.html>?

but if i change my query to this one everything is fine
SELECT COUNT(DISTINCT field1) as value1,
        CONCAT(field2, '') as value2
FROM table1,
        table2
GROUP BY value2

(here CONCAT(field2, '-') is replaced with CONCAT(field2, '') )

does anyone know what the matter is?

Does the simple query

  SELECT CONCAT('test', '-');

work or produce the same error?

ps
my mysql version is mysql Ver 14.7 Distrib 4.1.12, for unknown-freebsd4.6 (i386) using EditLine wrapper
and my system is FreeBSD 4.6

I've not used "EditLine wrapper" with mysql. Is there any chance it is doing something with '-'?

Michael



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