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: # [: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 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 CREATE TABLE 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.is_a?(Hash) ? native[:name] : native 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 specified" 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