整理多个技术点的sql综合应用：(开拓思路，SELECT子句内嵌子查询)续，用表变量替换临时表

--设定起始日期为当前年的第一天
DECLARE @dtDate DATETIME, @iRow INT 
SET @dtDate = DATEADD(yy, DATEDIFF(yy, 0, GETDATE()), 0)
SET @iRow = 10

--批量生成测试数据，日期规则递增的列、及随机的数值列
DECLARE @tmp TABLE( dtDate DATETIME, dcQty INT, dcTotalQty INT )
DECLARE @iRank INT
SET @iRank = 1

INSERT  INTO @tmp ( dtDate, dcQty )
VALUES  ( @dtDate, CHECKSUM(NEWID()) % 100 ) 
WHILE @iRank <= @iRow
BEGIN
    INSERT  INTO @tmp ( dtDate, dcQty )
            SELECT  DATEADD(DAY, @iRank, dtDate),
                    CHECKSUM(NEWID()) % 100
            FROM    @tmp
            WHERE   DATEADD(DAY, @iRank, dtDate) < DATEADD(DAY, @iRow, @dtDate)

    SET @iRank = @iRank * 2
END

--显示日期列、当前数值、累计数值
SELECT  a.dtDate,
        a.dcQty,
        ( SELECT    SUM(b.dcQty)
          FROM      @tmp AS b
          WHERE     b.dtDate <= a.dtDate
        ) AS dcTotalQty
FROM    @tmp AS a