Category: Programming Guides

All the little things you never bother to remember

Installing Software on Ubuntu Server 14.04

Install Oracle Java 7 on Ubuntu: sudo add-apt-repository ppa:webupd8team/java sudo apt-get update sudo apt-get install oracle-java7-set-default Install Glashfish 4 on Ubuntu: #Download Glassfish 4 wget download.java.net/glassfish/4.0/release/glassfish-4.0.zip #install the unzip program apt-get install unzip #unzip the glassfish zip to you /opt directory unzip glassfish-4.0.zip -d /opt #start glassfish app server /opt/glassfish4/bin/asadmin start-domain #change the admin password… Continue reading Installing Software on Ubuntu Server 14.04

Ignore Foreign Key Constraints During Truncate or Drop

If you are trying to drop/delete or empty/truncate a mysql table and you keep getting an error that you are violating a foreign key constraint, you may want to temporarily ignore that constraint. The code below demonstrates how you can tell mysql to ignore foreign key checks, delete/truncate the tables you need to, then re-enable… Continue reading Ignore Foreign Key Constraints During Truncate or Drop

Create new MySQL user and allow them to connect from any IP

If you are getting the error: user is not allowed to connect to this MySQL serverConnection closed by foreign host Or : Access denied for user ‘root’@’somehost.com’ (using password: YES)) Then you probably have not created your user properly in MySQL Here is how to create a new MySQL user and give him access to… Continue reading Create new MySQL user and allow them to connect from any IP

MySQL See all columns and tables that foreign key to a table or column

If you’re trying to understand how an existing database has been setup it can be very useful to see all of the tables/columns that foreign key into some other table/column. use INFORMATION_SCHEMA; select TABLE_NAME,COLUMN_NAME,CONSTRAINT_NAME, REFERENCED_TABLE_NAME,REFERENCED_COLUMN_NAME from KEY_COLUMN_USAGE where REFERENCED_TABLE_NAME = ‘your_table_name’ AND REFERENCED_COLUMN_NAME = ‘your_column_name’

Ruby MySQL Transaction Example

Here is a simple tutorial showing how to implement transactions in Ruby with MySQL. The code uses The MySQL2 Gem. We are showing the insert of 2 records into the customers table of a database. If either insert fails, both will be rolled back. require “mysql2” client_mysql = Mysql2::Client.new(:host =>; “localhost”, :username =>; “my_user”, :password… Continue reading Ruby MySQL Transaction Example