mssql - mazani duplicit

[pajkus]

dobrej napad!

ale: Only one expression can be specified in the select list when the subquery is not introduced with EXISTS.

tyhle slozitejsi sql dotazy nepouzival

EDIT: nebo lze pouze zapisovat data, ktery v tabulce nejsou ?
pro upresneni - duplicitni je cely radek

EDIT2:

delete from zamestnanci
where exists
  (select telefon, count(*)
   from zamestnanci
   group by telefon
   having count(*) > 1)

mi logicky smaze vsechny, ktery nejsou primo 1 - ja bych potreboval od kazdyho radku zachovat 1 unikatni