code: function del (table, filter) {
    let params = [table]
    let where = ''
    if (filter) {
      const wcolumns = Object.keys(filter)
      const wvalues = wcolumns.map(c => preparevalue(filter[c]))
      const wlen = wcolumns.length
      const wheres = keyvals(1, wlen).join(' AND ')
      where = ` WHERE ${wheres}`
      params = params.concat(wcolumns).concat(wvalues)
    }
    const sql = `DELETE FROM $1~${where};`
    return {sql, params}
  }
docs: Methods