alter table DT463 add DONE_ON_PL datetime2;
alter table DT463 add constraint DT463DI200000_DEFAULT DEFAULT CONVERT(datetime2,'01.01.1970',104) FOR [DONE_ON_PL];
update DT463 set DONE_ON_PL = DEFAULT;
alter table DT804 add DONE_ON_PL datetime2;
alter table DT804 add constraint DT804DI065037_DEFAULT DEFAULT CONVERT(datetime2,'01.01.1970',104) FOR [DONE_ON_PL];
update DT804 set DONE_ON_PL = DEFAULT;

