var tableList = ['cmdb_ci', 'cmdb_ci_building_facility', 'cmdb_ci_computer', 'cmdb_ci_display_hardware', 'cmdb_ci_hardware', 'cmdb_ci_ip_phone', 'cmdb_ci_ip_router', 'cmdb_ci_ip_switch', 'cmdb_ci_pc_hardware', 'cmdb_ci_peripheral', 'u_csas_itsm_cmdb_ci_hardware_mobile_device', 'u_csas_itsm_cmdb_ci_hardware_terminal', 'u_csas_itsm_cmdb_ci_pc_hardware_chromebook', 'u_csas_itsm_cmdb_ci_pc_hardware_laptop', 'u_csas_itsm_cmdb_ci_peripheral_bank_equipment', 'u_csas_itsm_cmdb_ci_peripheral_docking_station'];

var customField = {
  'u_1_level': '0debd807dbe5d30034def5e51d9619fe',
  'u_2_level': '0debd807dbe5d30034def5e51d9619fe',
  'u_3_level': '0debd807dbe5d30034def5e51d9619fe',
  'u_4_level': '0debd807dbe5d30034def5e51d9619fe',
  'u_ci_legacy_id': 666,
  'u_ci_legacy_system': 666,
  'u_critical_business_hours': '6699571edb525380f170f1c41d9619af',
  'u_floor': 666,
  'u_maintenance_vendor': 666,
  'u_must_be_checked': true,
  'u_operation_hours': '6699571edb525380f170f1c41d9619af',
  'u_room': 666
};

tableList.forEach(function(table) {
  var gr = new GlideRecord(table);
  gr.setLimit(1);
  gr.query();

  while (gr.next()) {
    for (var prop in customField) {
      gr.setValue(prop, customField[prop]);
      gr.update();
    }
  }
});