stream7

Backuping a single table from a database
mysqldump -u -p database_one -h host table_name > /var/www/backups/table_name.sql

Backuping a single table from a database with query
mysqldump -u #{user} -p#{pass} -h #{server} -nt --databases #{database} --tables #{table}  --where="#{query}" > example.sql
mysqldump -u root -prootpass -h ssserver -nt --databases example_development --tables products  --where="id > 7970001" > products.sql
-n -t for --no-create-db --no-create-info
mysqldump -u root -pmagrathea -h ssserver  --no-create-db --no-create-info --databases marvin_real3 --tables products  --where="id > 7970001" > pr2.sql

Restoring the table into another database

stream7

Nestable, sortable and dragable categories:

In the project I'm working on we wanted to have a Category model which we wanted to be nestable. But we also liked the user to have a draggable interface to manage and rearrange the order of his categories. So we chose awesome_nested_set for the model and jQuery.nestedSortable for the UI.

It took me some time to arrange things to work properly so I wanted to share my work in case it helps anybody.

Before beginning

you might want to take a look at a demo app

1. go to: http://awesomenestedsortable.heroku.com/groups/
2. click in show of any group

stream7

 literally always have to look up the meaning of :limit in migrations when it comes to integer values. Here's an overview. Now let's memorise it (oh, this works for MySQL, other databases may work differently):

:limit	    Numeric Type	Column Size	Max value
1	     tinyint	         1 byte	          127
2	     smallint	         2 bytes	32767
3	     mediumint	         3 byte	        8388607
nil, 4, 11    int(11)	         4 byte	       2147483647
5..8	      bigint	         8 byte	     9223372036854775807

Note: by default MySQL uses signed integers and Rails has no way (that I know of) to change this behaviour. Subsequently, the max. values noted are for signed integers.

stream7

For Rails 2:

ActiveRecord::Base.connection.instance_variable_set :@logger, Logger.new(STDOUT)

For Rails 3:

ActiveRecord::Base.logger = Logger.new(STDOUT)


taken form http://stackoverflow.com/questions/1344232/how-can-i-see-the-sql-that-will-be-generated-by-a-given-activerecord-query-in-rub