Represents an SQL table in an abstract way for updating a table. Also see TableDefinition and connection.create_table
Available transformations are:
change_table :table do |t|
  t.primary_key
  t.column
  t.index
  t.rename_index
  t.timestamps
  t.change
  t.change_default
  t.rename
  t.references
  t.belongs_to
  t.string
  t.text
  t.integer
  t.bigint
  t.float
  t.decimal
  t.numeric
  t.datetime
  t.timestamp
  t.time
  t.date
  t.binary
  t.boolean
  t.remove
  t.remove_references
  t.remove_belongs_to
  t.remove_index
  t.remove_timestamps
end
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| [R] | name | 
Changes the column's definition according to the new options.
t.change(:name, :string, limit: 80)
t.change(:description, :text)
See ActiveRecord::ConnectionAdapters::TableDefinition#column for details of the options you can use.
Sets a new default value for a column.
t.change_default(:qualification, 'new')
t.change_default(:authorized, 1)
t.change_default(:status, from: nil, to: "draft")
Adds a new column to the named table.
t.column(:name, :string)
See ActiveRecord::ConnectionAdapters::TableDefinition#column for details of the options you can use.
Checks to see if a column exists.
t.string(:name) unless t.column_exists?(:name, :string)
Adds a new index to the table. column_name can be a single Symbol, or an Array of Symbols.
t.index(:name)
t.index([:branch_id, :party_id], unique: true)
t.index([:branch_id, :party_id], unique: true, name: 'by_branch_party')
See connection.add_index for details of the options you can use.
Checks to see if an index exists.
unless t.index_exists?(:branch_id)
  t.index(:branch_id)
end
Adds a reference.
t.references(:user)
t.belongs_to(:supplier, foreign_key: true)
See connection.add_reference for details of the options you can use.
Removes the column(s) from the table definition.
t.remove(:qualification)
t.remove(:qualification, :experience)
Removes the given index from the table.
t.remove_index(:branch_id)
t.remove_index(column: [:branch_id, :party_id])
t.remove_index(name: :by_branch_party)
Removes a reference. Optionally removes a type column.
t.remove_references(:user)
t.remove_belongs_to(:supplier, polymorphic: true)
Removes the timestamp columns (created_at and
updated_at) from the table.
t.remove_timestamps
Renames the given index on the table.
t.rename_index(:user_id, :account_id)
Adds timestamps (created_at and updated_at)
columns to the table.
t.timestamps(null: false)