One database problem-find the smallest positive integer missing from the keycol column in table T1

Insert into DBO. t1 (keycol, datacol) values (4, 'B'); insert into DBO. t1 (keycol, datacol) values (6, 'C'); insert into DBO. t1 (keycol, datacol) values (7, 'D'); -- looking for the minimum missing integer for DBO. t1 keycol columnselect casewhen not exists (select * From DBO. t1 with (nolock) Where keycol = 1) then 1 else (select Min (1 +. keycol) from DBO. t1 as a with (nolock) where not exists (select * From DBO. t1 as B with (nolock) where. keycol + 1 = B. keycol) end; select Min (. keycol + 1) from DBO. t1 as
Left Outer Join DBO. T1 as B
On B. keycol =. keycol + 1 where B. keycol is null; declare @ min int, @ Max intset @ min = 1 select @ max = max (keycol) + 1 from DBO. t1 (nolock) print @ minprint @ maxwhile (@ min <@ max) begin; if not exists (select * From DBO. t1 (nolock) Where keycol = @ min) begin; print @ min; break; end; elseset @ min = @ min + 1end;