Method: Sequel::Dataset#count

Defined in:
lib/sequel/dataset/actions.rb

#count(arg = (no_arg=true), &block) ⇒ Object

Returns the number of records in the dataset. If an argument is provided, it is used as the argument to count. If a block is provided, it is treated as a virtual row, and the result is used as the argument to count.

DB[:table].count # SELECT count(*) AS count FROM table LIMIT 1
# => 3
DB[:table].count(:column) # SELECT count(column) AS count FROM table LIMIT 1
# => 2
DB[:table].count{foo(column)} # SELECT count(foo(column)) AS count FROM table LIMIT 1
# => 1



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# File 'lib/sequel/dataset/actions.rb', line 129

def count(arg=(no_arg=true), &block)
  if no_arg && !block
    cached_dataset(:_count_ds) do
      aggregate_dataset.select(COUNT_SELECT).single_value_ds
    end.single_value!.to_i
  else
    if block
      if no_arg
        arg = Sequel.virtual_row(&block)
      else
        raise Error, 'cannot provide both argument and block to Dataset#count'
      end
    end

    _aggregate(:count, arg)
  end
end