Creates a new table with the name table_name
.
table_name
may either be a String or a Symbol.
There are two ways to work with create_table
. You can use the
block form or the regular form, like this:
Block form
# create_table() passes a TableDefinition object to the block. # This form will not only create the table, but also columns for the # table. create_table(:suppliers) do |t| t.column :name, :string, limit: 60 # Other fields here end
Block form, with shorthand
# You can also use the column types as method calls, rather than calling the column method. create_table(:suppliers) do |t| t.string :name, limit: 60 # Other fields here end
Regular form
# Creates a table called 'suppliers' with no columns. create_table(:suppliers) # Add a column to 'suppliers'. add_column(:suppliers, :name, :string, {limit: 60})
The options
hash can include the following keys:
-
:id
-
Whether to automatically add a primary key column. Defaults to true. Join tables for
has_and_belongs_to_many
should set it to false. -
:primary_key
-
The name of the primary key, if one is to be added automatically. Defaults to
id
. If:id
is false this option is ignored.Note that Active Record models will automatically detect their primary key. This can be avoided by using
self.primary_key=
on the model to define the key explicitly. -
:options
-
Any extra options you want appended to the table definition.
-
:temporary
-
Make a temporary table.
-
:force
-
Set to true to drop the table before creating it. Defaults to false.
-
:as
-
SQL to use to generate the table. When this option is used, the block is ignored, as are the
:id
and:primary_key
options.
Add a backend specific option to the generated SQL (MySQL)
create_table(:suppliers, options: 'ENGINE=InnoDB DEFAULT CHARSET=utf8')
generates:
CREATE TABLE suppliers ( id int(11) DEFAULT NULL auto_increment PRIMARY KEY ) ENGINE=InnoDB DEFAULT CHARSET=utf8
Rename the primary key column
create_table(:objects, primary_key: 'guid') do |t| t.column :name, :string, limit: 80 end
generates:
CREATE TABLE objects ( guid int(11) DEFAULT NULL auto_increment PRIMARY KEY, name varchar(80) )
Do not add a primary key column
create_table(:categories_suppliers, id: false) do |t| t.column :category_id, :integer t.column :supplier_id, :integer end
generates:
CREATE TABLE categories_suppliers ( category_id int, supplier_id int )
Create a temporary table based on a query
create_table(:long_query, temporary: true, as: "SELECT * FROM orders INNER JOIN line_items ON order_id=orders.id")
generates:
CREATE TEMPORARY TABLE long_query AS SELECT * FROM orders INNER JOIN line_items ON order_id=orders.id
See also ActiveRecord::ConnectionAdapters::TableDefinition#column for details on how to create columns.
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