Selecting data from mysql using qt?

lyuts · wrote on 12 Oct 2010, 10:21

You put my debug before opening the connection. Put it after.

doforumda · wrote on 12 Oct 2010, 10:24

i changed db.lastError().text(); and place it after db.open()
this is the output
@
Starting /home/zafar/c++/dbExample-build-desktop/dbExample...
"Can't connect to local MySQL server through socket '/var/run/mysqld/mysqld.sock' (2) QMYSQL: Unable to connect"
false
QSqlQuery::exec: database not open
/home/zafar/c++/dbExample-build-desktop/dbExample exited with code 0
@

the commands in mysql displayed are here
repectively to your commands

mysql> use testTwo
Database changed
mysql> show tables
-> ;
+-------------------+
| Tables_in_testTwo |
+-------------------+
| testTable |
+-------------------+
1 row in set (0.01 sec)

@

doforumda · wrote on 12 Oct 2010, 10:38

any clues?

lyuts · wrote on 12 Oct 2010, 10:41

Change the 19th line to

@QSqlQuery query(db);@

doforumda · wrote on 12 Oct 2010, 10:43

same error again

lyuts · wrote on 12 Oct 2010, 10:46

Take a look into mysql logs to see what happens when you are trying to connect from your application.

doforumda · wrote on 12 Oct 2010, 10:49

how can i check that mysql logs and from where?

lyuts · wrote on 12 Oct 2010, 10:54

[quote author="doforumda" date="1286880547"]how can i check that mysql logs and from where? [/quote]

Try to find them:
@find /opt/lampp -name log -type d@

When you find the log directory, find a log for mysql and use tail utility:

@tail -f /path/to/mysql.log@

doforumda · wrote on 12 Oct 2010, 10:56

this command didnt return something
@
root@zafar-laptop:/# find /opt/lampp -name log -type d
root@zafar-laptop:/#
@

doforumda · wrote on 12 Oct 2010, 11:01

i have a folder inside lampp with the name logs. is it the one which your are talking about

lyuts · wrote on 12 Oct 2010, 11:01

Solution 1:
@find /opt/lampp -name '*.log'@
This might need sudo'ing.

Solution 2:
If 1st fails then you need to find the config files for mysql (it should be located in /opt/lampp directory) and try to find out what is the location of mysql's log files.

doforumda · wrote on 12 Oct 2010, 11:03

there are 6 files in there but no mysql.log

these are the files
access_log, cgisock.1693, error_log, httpd.pid, php_error_log, ssl_request_log

Dii · wrote on 12 Oct 2010, 11:04

Don't bother with the log files, I guess Qt looks at the wrong place for the socket file...

Let's check this line in your mysql config file (my.cnf):

socket = /var/run/mysqld/mysqld.sock

You should find my.cnf in /etc/ or /etc/mysql/ ... I don't know ubuntu that much.

doforumda · wrote on 12 Oct 2010, 11:05

1st solution returns this
@
root@zafar-laptop:/# find /opt/lampp -name *.log
/opt/lampp/htdocs/xampp/contrib/sqlnet.log
@

doforumda · wrote on 12 Oct 2010, 11:07

with which editor i can view that .conf file. with gedit or something.

lyuts · wrote on 12 Oct 2010, 11:07

[quote author="¤ Dii ¤" date="1286881470"]
You should find my.cnf in /etc/ or /etc/mysql/ ... I don't know ubuntu that much.[/quote]

I don't think that this config will be in /etc. He uses lampp - a preconfigured bundle. That config might be in /opt/lampp.

Dii · wrote on 12 Oct 2010, 11:08

BTW a quick sum:

mysql is installed
database and tables are created
access is granted
qt code looks fine

I see two possibilities here: libmysqlclient is missing, or the socket file is at different place.

doforumda · wrote on 12 Oct 2010, 11:09

the file my.cnf is in etc/mysql folder

Dii · wrote on 12 Oct 2010, 11:10

doforumda: use gedit

sudo gedit /etc/mysql/my.cnf

at least most of the ubuntu machines have the config file there.

doforumda · wrote on 12 Oct 2010, 11:10

this is the socket line in my.cnf

@
socket = /var/run/mysqld/mysqld.sock
@