Method: Sequel::Dataset#update

Defined in:

lib/sequel/dataset/actions.rb

#update(values = OPTS, &block) ⇒ Object

Updates values for the dataset. The returned value is the number of rows updated. values should be a hash where the keys are columns to set and values are the values to which to set the columns.

DB[:table].update(x: nil) # UPDATE table SET x = NULL
# => 10

DB[:table].update(x: Sequel[:x]+1, y: 0) # UPDATE table SET x = (x + 1), y = 0
# => 10

Some databases support using multiple tables in an UPDATE query. This requires multiple FROM tables (JOINs can also be used). As multiple FROM tables use an implicit CROSS JOIN, you should make sure your WHERE condition uses the appropriate filters for the FROM tables:

DB.from(:a, :b).join(:c, :d=>Sequel[:b][:e]).where{{a[:f]=>b[:g], a[:id]=>10}}.
  update(:f=>Sequel[:c][:h])
# UPDATE a
# SET f = c.h
# FROM b
# INNER JOIN c ON (c.d = b.e)
# WHERE ((a.f = b.g) AND (a.id = 10))

# File 'lib/sequel/dataset/actions.rb', line 1021

def update(values=OPTS, &block)
  sql = update_sql(values)
  if uses_returning?(:update)
    returning_fetch_rows(sql, &block)
  else
    execute_dui(sql)
  end
end