IF OBJECT_ID('tb1') IS NOT NULL
  DROP TABLE tb1
GO
CREATE TABLE tb1(ID int, OrderID varchar(10), Weight numeric(18, 6), AutoID int, 
                TotalWeight numeric(18,6), GroupID int);
GO
INSERT INTO tb1(ID, OrderID, Weight, AutoID, TotalWeight)
SELECT 3339, '12800389',  0.0238,  1,  0.0238 UNION ALL
SELECT 3339, '12800272',  0.045,  2,  0.0688 UNION ALL
SELECT 3339, '12800267',  0.133,  3,  0.2018 UNION ALL
SELECT 3339, '12800254',  0.75,  4,  0.9518 UNION ALL
SELECT 3339, '12800344',  0.365,  5,  1.3168 UNION ALL
SELECT 3339, '12800315',  0.047,  6,  1.3638 UNION ALL
SELECT 3339, '12800298',  0.137,  7,  1.5008 UNION ALL
SELECT 3339, '12794841',  0.765,  8,  2.2658 UNION ALL
SELECT 3339, '12794837',  0.765,  9,  3.0308 UNION ALL
SELECT 3339, '12786045',  0.8656,  10,  3.8964 UNION ALL
SELECT 3339, '12786042',  0.8656,  11,  4.762 UNION ALL
SELECT 3339, '12800679',  0.0332,  12,  4.7952 UNION ALL
SELECT 3339, '12800677',  0.0351,  13,  4.8303 UNION ALL
SELECT 3339, '12800633',  0.0577,  14,  4.888 UNION ALL
SELECT 3339, '12800602',  0.027,  15,  4.915;

--*****************************************************
--利用游标解决
declare @aID int, @wei numeric(18,6);
declare @GroupID int;
declare @sumWeight numeric(18,6);
declare @tmpT table(AutoID int, GroupID int);
set @sumWeight = 0;
set @GroupID = 0;

declare C CURSOR fast_forward for select AutoID, [Weight] from tb1 order by AutoID;
open C
fetch Next From C into @aID, @wei;
while @@FETCH_STATUS = 0
begin
    set @sumWeight = @sumWeight + @wei;
    if @sumWeight > 1.5
    begin
        set @GroupID = @GroupID + 1;
        insert into @tmpT(AutoID, GroupID) Values(@aID, @GroupID);
        set @sumWeight = @wei;
    end
    else begin
        insert into @tmpT(AutoID, GroupID) Values(@aID, @GroupID);
    end
    fetch Next From C into @aID, @wei;
end
Close C;
Deallocate C;
--更新原表的GroupID数据
update a
set a.GroupID = b.GroupID
from tb1 a
    join @tmpT b
    on a.AutoID = b.AutoID;

select * from Tb1;    

/*
ID          OrderID    Weight     Auto