Methods:
create_table(name, options)
drop_table(name)
rename_table(old_name, new_name)
add_column(table_name, column_name, type, options)
rename_column(table_name, column_name, new_column_name)
change_column(table_name, column_name, type, options)
remove_column(table_name, column_name)
add_index(table_name, column_name, index_type)
remove_index(table_name, column_name)
change_table(table_name) {|Table.new(table_name, self)| ...}
change_column_default(table_name, column_name, default)
change_column_null(table_name, column_name, null, default = nil)
Available Column Types (mappings are below):
* integer
* float
* datetime
* date
* timestamp
* time
* text
* string
* binary
* boolean
* decimal :precision, :scale
Valid Column Options:
* limit
* null (i.e. ":null => false" implies NOT NULL)
* default (to specify default values)
* :decimal, :precision => 8, :scale => 3
Rake Tasks:
rake db:schema:dump: run after you create a model to capture the schema.rb
rake db:schema:import: import the schema file into the current database (on
error, check if your schema.rb has ":force => true" on the create table
statements
./script/generate migration MigrationName: generate a new migration with a
new 'highest' version (run './script/generate migration' for this info at
your fingertips)
rake db:migrate: migrate your current database to the most recent version
rake db:migrate VERSION=5: migrate your current database to a specific
version (in this case, version 5)
rake db:rollback: migrate down one migration
rake db:rollback STEP=3: migrate down three migrations
rake db:migrate RAILS_ENV=production: migrate your production database
SQL:
Queries can be executed directly:
execute 'ALTER TABLE researchers ADD CONSTRAINT fk_researchers_departments
FOREIGN KEY ( department_id ) REFERENCES departments( id )'
Example Migration:
class UpdateUsersAndCreateProducts < ActiveRecord::Migration
def self.up
rename_column "users", "password", "hashed_password"
remove_column "users", "email"
User.reset_column_information
User.find(:all).each{|u| #do something with u}
create_table :people do |t|
t.integer :account_id
t.string :first_name, :last_name, :null => false
t.text :description
t.references :category # is the equivalent of t.integer :category_id
t.timestamps
end
end
migrations:
Methods:
create_table(name, options)
drop_table(name)
rename_table(old_name, new_name)
add_column(table_name, column_name, type, options)
rename_column(table_name, column_name, new_column_name)
change_column(table_name, column_name, type, options)
remove_column(table_name, column_name)
add_index(table_name, column_name, index_type)
remove_index(table_name, column_name)
change_table(table_name) {|Table.new(table_name, self)| ...}
change_column_default(table_name, column_name, default)
change_column_null(table_name, column_name, null, default = nil)
Available Column Types (mappings are below):
* integer
* float
* datetime
* date
* timestamp
* time
* text
* string
* binary
* boolean
* decimal :precision, :scale
Valid Column Options:
* limit
* null (i.e. ":null => false" implies NOT NULL)
* default (to specify default values)
* :decimal, :precision => 8, :scale => 3
Rake Tasks:
rake db:schema:dump: run after you create a model to capture the schema.rb
rake db:schema:import: import the schema file into the current database (on
error, check if your schema.rb has ":force => true" on the create table
statements
./script/generate migration MigrationName: generate a new migration with a
new 'highest' version (run './script/generate migration' for this info at
your fingertips)
rake db:migrate: migrate your current database to the most recent version
rake db:migrate VERSION=5: migrate your current database to a specific
version (in this case, version 5)
rake db:rollback: migrate down one migration
rake db:rollback STEP=3: migrate down three migrations
rake db:migrate RAILS_ENV=production: migrate your production database
SQL:
Queries can be executed directly:
execute 'ALTER TABLE researchers ADD CONSTRAINT fk_researchers_departments
FOREIGN KEY ( department_id ) REFERENCES departments( id )'
Example Migration:
class UpdateUsersAndCreateProducts < ActiveRecord::Migration
def self.up
rename_column "users", "password", "hashed_password"
remove_column "users", "email"
User.reset_column_information
User.find(:all).each{|u| #do something with u}
create_table :people do |t|
t.integer :account_id
t.string :first_name, :last_name, :null => false
t.text :description
t.references :category # is the equivalent of t.integer :category_id
t.timestamps
end
end
def self.down
rename_column "users", "hashed_password", "password"
add_column "users", "email", :string
drop_table "products"
end
end
Find Highest version:
script/runner "puts ActiveRecord::Migrator.current_version"
Database Mapping
Rails db2 mysql openbase Oracle
:binary blob(32678) blob object blob
:boolean decimal(1) tinyint(1) boolean number(10)
:date date date date date
:datetime timestamp datetime datetime date
:decimal decimal decimal decimal decimal
:float float float float number
:integer int int(11) integer number(38)
:string varchar(255) varchar(255) char(4096) varchar2(255)
:text clob(32768) text text clob
:time time time time date
:timestamp timestamp datetime timestamp date
Rails postgresql sqlite sqlserver Sybase
:binary bytea blob image image
:boolean boolean boolean bit bit
:date date date datetime datetime
:datetime timestamp datetime datetime datetime
:decimal decimal decimal decimal decimal
:float float float float(8) float(8)
:integer integer integer int int
:string * varchar(255) varchar(255) varchar(255)
:text text text text text
:time time datetime datetime time
:timestamp timestamp datetime datetime timestamp
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