[Source]

     # File vendor/rails/activerecord/lib/active_record/connection_adapters/abstract/schema_definitions.rb, line 228
228:       def initialize(base)
229:         @columns = []
230:         @base = base
231:       end

Returns a ColumnDefinition for the column with name name.

[Source]

     # File vendor/rails/activerecord/lib/active_record/connection_adapters/abstract/schema_definitions.rb, line 240
240:       def [](name)
241:         @columns.find {|column| column.name.to_s == name.to_s}
242:       end

Instantiates a new column for the table. The type parameter must be one of the following values: :primary_key, :string, :text, :integer, :float, :decimal, :datetime, :timestamp, :time, :date, :binary, :boolean.

Available options are (none of these exists by default):

• :limit: Requests a maximum column length (:string, :text, :binary or :integer columns only)
• :default: The column’s default value. You cannot explicitely set the default value to NULL. Simply leave off this option if you want a NULL default value.
• :null: Allows or disallows NULL values in the column. This option could have been named :null_allowed.
• :precision: Specifies the precision for a :decimal column.
• :scale: Specifies the scale for a :decimal column.

Please be aware of different RDBMS implementations behavior with :decimal columns:

• The SQL standard says the default scale should be 0, :scale <= :precision, and makes no comments about the requirements of :precision.
• MySQL: :precision [1..63], :scale [0..30]. Default is (10,0).
• PostGres?: :precision [1..infinity], :scale [0..infinity]. No default.
• Sqlite2: Any :precision and :scale may be used. Internal storage as strings. No default.
• Sqlite3: No restrictions on :precision and :scale, but the maximum supported :precision is 16. No default.
• Oracle: :precision [1..38], :scale [-84..127]. Default is (38,0).
• DB2: :precision [1..63], :scale [0..62]. Default unknown.
• Firebird: :precision [1..18], :scale [0..18]. Default (9,0). Internal types NUMERIC and DECIMAL have different storage rules, decimal being better.
• FrontBase?: :precision [1..38], :scale [0..38]. Default (38,0). WARNING Max :precision/:scale for NUMERIC is 19, and DECIMAL is 38.
• SqlServer?: :precision [1..38], :scale [0..38]. Default (38,0).
• Sybase: :precision [1..38], :scale [0..38]. Default (38,0).
• OpenBase?: Documentation unclear. Claims storage in double.

This method returns self.

Examples

 # Assuming td is an instance of TableDefinition
 td.column(:granted, :boolean)
   #=> granted BOOLEAN

 td.column(:picture, :binary, :limit => 2.megabytes)
   #=> picture BLOB(2097152)

 td.column(:sales_stage, :string, :limit => 20, :default => 'new', :null => false)
   #=> sales_stage VARCHAR(20) DEFAULT 'new' NOT NULL

 def.column(:bill_gates_money, :decimal, :precision => 15, :scale => 2)
   #=> bill_gates_money DECIMAL(15,2)

 def.column(:sensor_reading, :decimal, :precision => 30, :scale => 20)
   #=> sensor_reading DECIMAL(30,20)

 # While <tt>:scale</tt> defaults to zero on most databases, it
 # probably wouldn't hurt to include it.
 def.column(:huge_integer, :decimal, :precision => 30)
   #=> huge_integer DECIMAL(30)

[Source]

     # File vendor/rails/activerecord/lib/active_record/connection_adapters/abstract/schema_definitions.rb, line 319
319:       def column(name, type, options = {})
320:         column = self[name] || ColumnDefinition.new(@base, name, type)
321:         column.limit = options[:limit] || native[type.to_sym][:limit] if options[:limit] or native[type.to_sym]
322:         column.precision = options[:precision]
323:         column.scale = options[:scale]
324:         column.default = options[:default]
325:         column.null = options[:null]
326:         @columns << column unless @columns.include? column
327:         self
328:       end

Appends a primary key definition to the table definition. Can be called multiple times, but this is probably not a good idea.

[Source]

     # File vendor/rails/activerecord/lib/active_record/connection_adapters/abstract/schema_definitions.rb, line 235
235:       def primary_key(name)
236:         column(name, native[:primary_key])
237:       end

Returns a String whose contents are the column definitions concatenated together. This string can then be pre and appended to to generate the final SQL to create the table.

[Source]

     # File vendor/rails/activerecord/lib/active_record/connection_adapters/abstract/schema_definitions.rb, line 333
333:       def to_sql
334:         @columns * ', '
335:       end