Database concurrent access issue

Dear All,

I have this .NET application that inserts lucky draw entries into SQL server. Each entry may have a range of values that the winning number will be drawn from. For example,

Entry 1: [1, 2]
Entry 2: [3, 8]
Entry 3: [9, 10]
Entry 4: [11, 11]
Entry 5: [12, 20]

The winning number will be picked from [1, 20]. Given this scenario, what is the best design that can handle the concurrency issue? If two entries are input at the same time, how to make sure it won't have the same starting value? Anyway to lock a table when one is accessing, disallowing other to run select query?

Thanks.You'll have to explain that better.|||For example, Entry 3: [9, 10] means Entry 3 has the number range starting from 9 and ending at 10.

The winning number will be drawn from the number range.

You'll have to explain that better.|||Clear as mud.

If you want to ensure two entries do not share the same starting value, then make the starting value the primary key or a unique index.|||blindman: qxz wants to validate new entries to ensure that it does not conflict with any existing entry and wants to enforce this validation in case of multiple users updating the Db same time...

qxz: a table lock is needed to ensure proper insert. remember explicit locks can have negative effect on performance

create procedure CheckIt (@.StVal int, @.EndVal int)
as

BEGIN TRANSACTION
declare @.CheckFailed char(1)
set @.CheckFailed = 'N'
if exists (select * from MyTable with (tablockx) where @.StVal between StartVal and EndVal)
set @.CheckFailed = 'Y'
if exists (select * from MyTable where @.EndVal between StartVal and EndVal)
set @.CheckFailed = 'Y'

if @.CheckFailed = 'Y'
begin
ROLLBACK TRANSACTION
return 0
end
else
begin
insert into MyTable .....
COMMIT TRANSACTION
return 1
end