How to convert a table column to another data type

Posted by holden on Stack Overflow See other posts from Stack Overflow or by holden
Published on 2010-05-21T11:50:17Z Indexed on 2010/05/21 12:10 UTC
Read the original article Hit count: 249

Filed under:

ruby-on-rails

|

postgresql

|

alter-table

|

migration

|

datatypes

I have a column with the type of Varchar in my Postgres database which I meant to be integers... and now I want to change them, unfortunately this doesn't seem to work using my rails migration.

change_column :table1, :columnB, :integer

So I tried doing this:

execute 'ALTER TABLE "table1" ALTER COLUMN "columnB" TYPE integer USING CAST(columnB AS INTEGER)'

but cast doesn't work in this instance because some of the column are null...

any ideas?

© Stack Overflow or respective owner

Related posts about ruby-on-rails

Ruby on Rails - How can I start? [closed]

as seen on Programmers - Search for 'Programmers'
I have misconception in understanding the relationship between Ruby language and Ruby on Rails Framework. Because of 'I am an absolute beginner' in web development I have no idea if I have to grasp the fundamentals of Ruby before I go with Ruby on Rails! I also want to ask who is behind both Ruby… >>> More
DES3 decryption in Ruby on Rails

as seen on Stack Overflow - Search for 'Stack Overflow'
My RoR server receives a string, that was encrypted in C++ application using des3 with base64 encoding The cipher object is created so: cipher = OpenSSL::Cipher::Cipher::new("des3") cipher.key = key_str cipher.iv = iv_str key_str and iv_str: are string representations of key and initialization… >>> More
Ruby on rails: Image downloads with Authentication/Authorization/Time outs

as seen on Stack Overflow - Search for 'Stack Overflow'
Hi Guys, I'm having few doubts on implementing file downloads. I'm creating an app where I use attachment_fu with Amazon s3 to upload files. Things are working pretty well so far on uploading side. Now its the time to start the file downloads. Here is what I need, a logged in user search and browse… >>> More
Ruby on Rails deployment, on "thin" server with lot of attachments

as seen on Stack Overflow - Search for 'Stack Overflow'
A lot of PDFs are stored inside MySQL as a BLOB field for each PDF file. The average file size is 500K each. The Rails app will stream the :binary data as file downloads, where there is a user click on the download link. Assume there is a maximum of 5 users downloading 5 PDFs concurrently, what… >>> More
Apply Behavior Driven Development to Ruby on Rails with Rspec

as seen on Internet.com - Search for 'Internet.com'
Applying the Behavior Driven Development (BDD) methodology to your Rails development takes you beyond traditional Test Driven Development. Learn how to do it with the Ruby-based BDD framework RSpec. >>> More

Related posts about postgresql

Postgresql fails to start on Ubuntu 10.04.4 LTS

as seen on Ask Ubuntu - Search for 'Ask Ubuntu'
I installed postgresql 9.2 from add-apt-repository ppa:pitti/postgresql using apt-get install postgresql-9.2 At the end of the install and every time I try to launch postgresql by using the following command /etc/init.d/postgresql start or service postgresql start I get this error: Error:… >>> More
can't install psycopg2 in my env on mac os x lion

as seen on Server Fault - Search for 'Server Fault'
I tried install psycopg2 via pip in my virtual env, but got this error: ld: library not found for -lpq (full log here: http://pastebin.com/XdmGyJ4u ) I tried install postgres 9.1 from .dmg and via port, (gksks)iMac-Alexander:~ lorddaedra$ locate libpq /Developer/SDKs/MacOSX10.7.sdk/usr/include/libpq /Developer/SDKs/MacOSX10… >>> More
Postgresql has broken apt-get on Ubuntu

as seen on Super User - Search for 'Super User'
On ubuntu 12.04, whenever I try to install a package using apt-get I'm greeted by: The following packages have unmet dependencies: postgresql-9.1 : Depends: postgresql-client-9.1 but it is not going to be instal led E: Unmet dependencies. Try 'apt-get -f install' with no packages (or specify a so lution)… >>> More
Installing PostgreSQL on FreeBSD (with ports)

as seen on Server Fault - Search for 'Server Fault'
Hey everyone, I am trying to install (using ports) PostgreSQL on a virtual server, running FreeBSD. My one question is this: Which of the following should I install? postgresql-contrib postgresql-docs postgresql-jdbc postgresql-libpgeasy postgresql-libpq++ postgresql-libpqxx postgresql-odbc … >>> More
Strange permission errors in new PostgreSQL installation

as seen on Server Fault - Search for 'Server Fault'
A freshly installed PostgreSQL (with configuration overwritten) won't start: $ sudo service postgresql start * Starting PostgreSQL 9.1 database server * Error: could not read /etc/postgresql/9.1/main/postgresql.conf: Permission denied Looks like it should be able to read it though: $ ls -l postgresql… >>> More