ActiveRecord::ConnectionAdapters::SchemaStatements

add_column(table_name, column_name, type, options = {})

Adds a new column to the named table. See ActiveRecord::ConnectionAdapters::TableDefinition#column for details of the options you can use.

Source: show

# File rails/activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb, line 121
def add_column(table_name, column_name, type, options = {})
  add_column_sql = "ALTER TABLE #{table_name} ADD #{quote_column_name(column_name)} #{type_to_sql(type, options[:limit], options[:precision], options[:scale])}"
  add_column_options!(add_column_sql, options)
  execute(add_column_sql)
end

add_index(table_name, column_name, options = {})

Adds a new index to the table. column_name can be a single Symbol, or an Array of Symbols.

The index will be named after the table and the first column names, unless you pass :name as an option.

When creating an index on multiple columns, the first column is used as a name for the index. For example, when you specify an index on two columns [:first, :last], the DBMS creates an index for both columns as well as an index for the first colum :first. Using just the first name for this index makes sense, because you will never have to create a singular index with this name.

Examples

Creating a simple index

add_index(:suppliers, :name)

generates

CREATE INDEX suppliers_name_index ON suppliers(name)

Creating a unique index

add_index(:accounts, [:branch_id, :party_id], :unique => true)

generates

CREATE UNIQUE INDEX accounts_branch_id_party_id_index ON accounts(branch_id, party_id)

Creating a named index

add_index(:accounts, [:branch_id, :party_id], :unique => true, :name => 'by_branch_party')

generates

CREATE UNIQUE INDEX by_branch_party ON accounts(branch_id, party_id)

Source: show

# File rails/activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb, line 186
def add_index(table_name, column_name, options = {})
  column_names = Array(column_name)
  index_name   = index_name(table_name, :column => column_names)

  if Hash === options # legacy support, since this param was a string
    index_type = options[:unique] ? "UNIQUE" : ""
    index_name = options[:name] || index_name
  else
    index_type = options
  end
  quoted_column_names = column_names.map { |e| quote_column_name(e) }.join(", ")
  execute "CREATE #{index_type} INDEX #{quote_column_name(index_name)} ON #{table_name} (#{quoted_column_names})"
end

add_order_by_for_association_limiting!(sql, options)

ORDER BY clause for the passed order option. PostgreSQL overrides this due to its stricter standards compliance.

Source: show

# File rails/activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb, line 293
def add_order_by_for_association_limiting!(sql, options)
  sql << "ORDER BY #{options[:order]}"
end

change_column(table_name, column_name, type, options = {})

Changes the column’s definition according to the new options. See ActiveRecord::ConnectionAdapters::TableDefinition#column for details of the options you can use.

Examples

change_column(:suppliers, :name, :string, :limit => 80)
change_column(:accounts, :description, :text)

Source: show

# File rails/activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb, line 139
def change_column(table_name, column_name, type, options = {})
  raise NotImplementedError, "change_column is not implemented"
end

change_column_default(table_name, column_name, default)

Sets a new default value for a column. If you want to set the default value to NULL, you are out of luck. You need to ActiveRecord::ConnectionAdapters::DatabaseStatements#execute the apppropriate SQL statement yourself.

Examples

change_column_default(:suppliers, :qualification, 'new')
change_column_default(:accounts, :authorized, 1)

Source: show

# File rails/activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb, line 149
def change_column_default(table_name, column_name, default)
  raise NotImplementedError, "change_column_default is not implemented"
end

columns(table_name, name = nil)

Returns an array of Column objects for the table specified by table_name. See the concrete implementation for details on the expected parameter values.

Source: show

# File rails/activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb, line 28
def columns(table_name, name = nil) end

create_table(name, options = {})

Creates a new table 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() yields a TableDefinition instance
create_table(:suppliers) do |t|
  t.column :name, :string, :limit => 60
  # Other fields here
end

Regular form

create_table(: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 :id => false.
:primary_key: The name of the primary key, if one is to be added automatically. Defaults to id.
:options: Any extra options you want appended to the table definition.
:temporary: Make a temporary table.
:force: Set to true or false to drop the table before creating it. Defaults to false.

Examples

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_join (
  category_id int,
  supplier_id int
)

See also ActiveRecord::ConnectionAdapters::TableDefinition#column for details on how to create columns.

Source: show

# File rails/activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb, line 90
def create_table(name, options = {})
  table_definition = TableDefinition.new(self)
  table_definition.primary_key(options[:primary_key] || "id") unless options[:id] == false

  yield table_definition

  if options[:force]
    drop_table(name, options) rescue nil
  end

  create_sql = "CREATE#{' TEMPORARY' if options[:temporary]} TABLE "
  create_sql << "#{name} ("
  create_sql << table_definition.to_sql
  create_sql << ") #{options[:options]}"
  execute create_sql
end

distinct(columns, order_by)

SELECT DISTINCT clause for a given set of columns and a given ORDER BY clause. Both PostgreSQL and Oracle overrides this for custom DISTINCT syntax.

distinct("posts.id", "posts.created_at desc")

Source: show

# File rails/activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb, line 287
def distinct(columns, order_by)
  "DISTINCT #{columns}"
end

drop_table(name, options = {})

Drops a table from the database.

Source: show

# File rails/activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb, line 115
def drop_table(name, options = {})
  execute "DROP TABLE #{name}"
end

initialize_schema_information()

Should not be called normally, but this operation is non-destructive. The migrations module handles this automatically.

Source: show

# File rails/activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb, line 235
def initialize_schema_information
  begin
    execute "CREATE TABLE #{ActiveRecord::Migrator.schema_info_table_name} (version #{type_to_sql(:integer)})"
    execute "INSERT INTO #{ActiveRecord::Migrator.schema_info_table_name} (version) VALUES(0)"
  rescue ActiveRecord::StatementInvalid
    # Schema has been intialized
  end
end

native_database_types()

Returns a Hash of mappings from the abstract data types to the native database types. See ActiveRecord::ConnectionAdapters::TableDefinition#column for details on the recognized abstract data types.

Source: show

# File rails/activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb, line 7
def native_database_types
  {}
end

remove_column(table_name, column_name)

Removes the column from the table definition.

Examples

remove_column(:suppliers, :qualification)

Source: show

# File rails/activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb, line 130
def remove_column(table_name, column_name)
  execute "ALTER TABLE #{table_name} DROP #{quote_column_name(column_name)}"
end

remove_index(table_name, options = {})

Remove the given index from the table.

Remove the suppliers_name_index in the suppliers table.

remove_index :suppliers, :name

Remove the index named accounts_branch_id_index in the accounts table.

remove_index :accounts, :column => :branch_id

Remove the index named accounts_branch_id_party_id_index in the accounts table.

remove_index :accounts, :column => [:branch_id, :party_id]

Remove the index named by_branch_party in the accounts table.

remove_index :accounts, :name => :by_branch_party

Source: show

# File rails/activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb, line 210
def remove_index(table_name, options = {})
  execute "DROP INDEX #{quote_column_name(index_name(table_name, options))} ON #{table_name}"
end

rename_column(table_name, column_name, new_column_name)

Renames a column.

Example

rename_column(:suppliers, :description, :name)

Source: show

# File rails/activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb, line 156
def rename_column(table_name, column_name, new_column_name)
  raise NotImplementedError, "rename_column is not implemented"
end

rename_table(name, new_name)

Renames a table.

Example

rename_table('octopuses', 'octopi')

Source: show

# File rails/activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb, line 110
def rename_table(name, new_name)
  raise NotImplementedError, "rename_table is not implemented"
end

structure_dump()

Returns a string of CREATE TABLE SQL statement(s) for recreating the entire structure of the database.

Source: show

# File rails/activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb, line 230
def structure_dump
end

table_alias_for(table_name)

Truncates a table alias according to the limits of the current adapter.

Source: show

# File rails/activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb, line 17
def table_alias_for(table_name)
  table_name[0..table_alias_length-1].gsub(%r\./, '_')
end

table_alias_length()

This is the maximum length a table alias can be

Source: show

# File rails/activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb, line 12
def table_alias_length
  255
end

options_include_default?(options)

Source: show

# File rails/activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb, line 298
def options_include_default?(options)
  options.include?(:default) && !(options[:null] == false && options[:default].nil?)
end

Module ActiveRecord::ConnectionAdapters::SchemaStatements

Examples

Creating a simple index

Creating a unique index

Creating a named index

Examples

Examples

Block form

Regular form

Examples

Add a backend specific option to the generated SQL (MySQL)

Rename the primary key column

Do not add a primary key column

Examples

Example

Example