Prevent a Stored Procedure from being executed twice at the same time

Question

I have a stored procedure for SQL Server 2000 that can only have a single instance being executed at any given moment. Is there any way to check and ensure that the procedur

Answer 1

At the start of the procedure check if piece of data is 'locked' if not lock it

At end of procedure unlock the piece of data.

ie

SELECT @IsLocked=IsLocked FROM CheckLockedTable Where spName = 'this_storedProcedure'

IF @IsLocked = 1
    RETURN
ELSE
    UPDATE CheckLockedTable SET IsLocked = 1 Where spName = 'this_storedProcedure'

.
.
.

-- At end of Stored Procedure
    UPDATE CheckLockedTable SET IsLocked = 0 Where spName = 'this_storedProcedure'