Everyday Internet Stuff » MySQL

MySQL Error: Data truncated for column ‘…’ at row 0

admin — Fri, 12 Nov 2010 23:15:27 +0000

If you’ve recently migrated from MySQL 4 to MySQL 5, queries that used to work might cause errors. The thing is that MySQL got much more struct about what data can go where. MySQL 4 used to cast NULL values to 0 INT, DOUBLE, FLOAT etc implicitly. MySQL 5 doesn’t do it so you ether need to make the column you are trying to assign to NULLable or make sure that it is never assigned NULL value.

Backup large MySQL database without SSH access

admin — Sun, 14 Jun 2009 06:41:26 +0000

Moving your databases around is easy when they are small. When they get large it may become a problem especially if you are on a shared hosting…

One of my website’s database grew to 5.5Gb in size. When it’s that big phpMyAdmin and standard control panel backup scripts just don’t work. Fortunately there is a great solution: MysqlDumper.de (english translation). It’s PHP/AJAX application that backs up and restores your databases part by part. It’s really straightforward to use.

It took it 10+ hours to export by 5.5Gb database as 700Mb of GZipped SQL scripts but it got the job done 100%. Another nice touch about it is that it allows you to break down your backups into parts so you can start restoring the database at the new location the moment first part is ready. This can be quite useful since when you are restoring database this big reconstructing indexes can take a very long time.

Mysql Connector Set Variable

admin — Sat, 06 Jun 2009 01:07:35 +0000

MySql is a nice database engine, C# is nice programming language. However when you put them together you get something not nice at all. At least from a viewpoint of someone like me who is spoiled by nice, clean and seamless database integration Linq for SQL provides for MSSQL. Unfortunately when you put together MSSQL and PHP you also get an ugly thing that doesn’t quite work.

One of the main problems with integrating MySQL with .NET languages is complete lack of documentation for MySQL Connector. CHM file that comes bundled with it is a joke – it merely lists class members and has a couple of stub articles. There are some sample pieces of code but after that you are on your own.

Just recently I ran into a problem of not being able to SQL variable from query. If you write something like this:

using (MySqlCommand cmd = this.mySql.CreateCommand())
{
cmd.CommandText = “SET @today=DATE(NOW())”;
return cmd.ExecuteNonQuery();
}

you’ll get “Parameter ‘today’ must be defined.” exception. I searched the internet and only thing I could find was this message from mysql .net maillist with no replies. Typical shortcoming of open-source of nobody wanting to do the dirty work of documenting their code properly is somewhat offset by the fact that you can poke around the code yourself. So I did.

Solution is there but it’s anything but obvoius – append Allow User Variables=true; to your MySQL connection string. This will cause MySql connector to skip checking parameters mentioned in the query for existence. There is a downside to this solution – you’ll not be able to easily catch bugs in your code caused by mistyped query parameter names.

Hopefully at some point MySql connector developers will realize that passings parameters into query and settings MySQL connection variables are two different pieces of functionality and each should have it’s own independent syntax.