DECLARE @Demoid INT = - 1;

DECLARE @Recordcount INT = 1;
DECLARE @TotalRecords INT = 0; 
DECLARE @Min BIGINT, @Max BIGINT;

SELECT @Min = 100000, @Max = 10000000;

SELECT TOP (@Max - @Min + 1) @Min - 1 + ROW NUMBER() OVER (ORDER BY t1.number) AS N 
INTO #SequenceNumbersWinthinRange 
FROM MASTER..spt_values t1 
CROSS JOIN MASTER..spt_values t2;

CREATE TABLE #TableRows AS (ID INT IDENTITY(l,1) NOT NULL, DemoId INT NOT NULL); 

INSERT INTO #TableRows (DemoId)
SELECT ID FROM demo;

SET @TotalRecords = @@rowcount; 

WHILE @TotalRecords >= @RecordCount 
BEGIN

SELECT @Demoid = DemoId FROM #TableRows WHERE ID = @RecordCount; 

UPDATE demo
SET Name =(SELECT MIN(N) FROM #SequenceNumbersWinthinRange WHERE N NOT IN (SELECT Name FROM Demo)) 
WHERE ID = @Demoid; 

SELECT @RecordCount = @RecordCount + 1, @Demoid = -1; 
END ;