def create_sql(table,charset='UTF8')
      sql    = "CREATE TABLE #{table} ("
      fields = vectors.to_a.collect do |f|
        v = self[f]
        f.to_s + ' ' + v.db_type
      end

      sql + fields.join(",\n ")+") CHARACTER SET=#{charset};"
    end
Create a sql, basen on a given Dataset

== Arguments

* table - String specifying name of the table that will created in SQL.
* charset - Character set. Default is "UTF8".

@example

ds = Daru::DataFrame.new({
:id   => Daru::Vector.new([1,2,3,4,5]),
:name => Daru::Vector.new(%w{Alex Peter Susan Mary John})
})
ds.create_sql('names')
#=>"CREATE TABLE names (id INTEGER,\n name VARCHAR (255)) CHARACTER SET=UTF8;"