module ActiveRecord
module ConnectionAdapters # :nodoc:
module SchemaStatements
# Returns a Hash of mappings from the abstract data types to the native
# database types. See TableDefinition#column for details on the recognized
# abstract data types.
def native_database_types
{}
end
# This is the maximum length a table alias can be
def table_alias_length
255
end
# Truncates a table alias according to the limits of the current adapter.
def table_alias_for(table_name)
table_name[0..table_alias_length-1].gsub(/\./, '_')
end
# def tables(name = nil) end
# Returns an array of indexes for the given table.
# def indexes(table_name, name = nil) end
# Returns an array of Column objects for the table specified by +table_name+.
# See the concrete implementation for details on the expected parameter values.
def columns(table_name, name = nil) end
# 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:
# [<tt>:id</tt>]
# Whether to automatically add a primary key column. Defaults to true.
# Join tables for has_and_belongs_to_many should set :id => false.
# [<tt>:primary_key</tt>]
# The name of the primary key, if one is to be added automatically.
# Defaults to +id+.
# [<tt>:options</tt>]
# Any extra options you want appended to the table definition.
# [<tt>:temporary</tt>]
# Make a temporary table.
# [<tt>:force</tt>]
# 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 TableDefinition#column for details on how to create columns.
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
# Renames a table.
# ===== Example
# rename_table('octopuses', 'octopi')
def rename_table(name, new_name)
raise NotImplementedError, "rename_table is not implemented"
end
# Drops a table from the database.
def drop_table(name, options = {})
execute "DROP TABLE #{name}"
end
# Adds a new column to the named table.
# See TableDefinition#column for details of the options you can use.
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
# Removes the column from the table definition.
# ===== Examples
# remove_column(:suppliers, :qualification)
def remove_column(table_name, column_name)
execute "ALTER TABLE #{table_name} DROP #{quote_column_name(column_name)}"
end
# Changes the column's definition according to the new options.
# See TableDefinition#column for details of the options you can use.
# ===== Examples
# change_column(:suppliers, :name, :string, :limit => 80)
# change_column(:accounts, :description, :text)
def change_column(table_name, column_name, type, options = {})
raise NotImplementedError, "change_column is not implemented"
end
# 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
# DatabaseStatements#execute the apppropriate SQL statement yourself.
# ===== Examples
# change_column_default(:suppliers, :qualification, 'new')
# change_column_default(:accounts, :authorized, 1)
def change_column_default(table_name, column_name, default)
raise NotImplementedError, "change_column_default is not implemented"
end
# Renames a column.
# ===== Example
# rename_column(:suppliers, :description, :name)
def rename_column(table_name, column_name, new_column_name)
raise NotImplementedError, "rename_column is not implemented"
end
# 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)
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
# 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
def remove_index(table_name, options = {})
execute "DROP INDEX #{quote_column_name(index_name(table_name, options))} ON #{table_name}"
end
def index_name(table_name, options) #:nodoc:
if Hash === options # legacy support
if options[:column]
"index_#{table_name}_on_#{Array(options[:column]) * '_and_'}"
elsif options[:name]
options[:name]
else
raise ArgumentError, "You must specify the index name"
end
else
index_name(table_name, :column => options)
end
end
# Returns a string of <tt>CREATE TABLE</tt> SQL statement(s) for recreating the
# entire structure of the database.
def structure_dump
end
# Should not be called normally, but this operation is non-destructive.
# The migrations module handles this automatically.
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
def dump_schema_information #:nodoc:
begin
if (current_schema = ActiveRecord::Migrator.current_version) > 0
return "INSERT INTO #{ActiveRecord::Migrator.schema_info_table_name} (version) VALUES (#{current_schema})"
end
rescue ActiveRecord::StatementInvalid
# No Schema Info
end
end
def type_to_sql(type, limit = nil, precision = nil, scale = nil) #:nodoc:
native = native_database_types[type]
column_type_sql = native[:name]
if type == :decimal # ignore limit, use precison and scale
precision ||= native[:precision]
scale ||= native[:scale]
if precision
if scale
column_type_sql << "(#{precision},#{scale})"
else
column_type_sql << "(#{precision})"
end
else
raise ArgumentError, "Error adding decimal column: precision cannot be empty if scale if specifed" if scale
end
column_type_sql
else
limit ||= native[:limit]
column_type_sql << "(#{limit})" if limit
column_type_sql
end
end
def add_column_options!(sql, options) #:nodoc:
sql << " DEFAULT #{quote(options[:default], options[:column])}" if options_include_default?(options)
sql << " NOT NULL" if options[:null] == false
end
# 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")
def distinct(columns, order_by)
"DISTINCT #{columns}"
end
# ORDER BY clause for the passed order option.
# PostgreSQL overrides this due to its stricter standards compliance.
def add_order_by_for_association_limiting!(sql, options)
sql << "ORDER BY #{options[:order]}"
end
protected
def options_include_default?(options)
options.include?(:default) && !(options[:null] == false && options[:default].nil?)
end
end
end
end
