低速SQL查询

试试这样的- 避免 任何 一排排痛苦的排 类似光标或while循环的处理:

-- creates a temporary "inline" view of the data you're interested in and 
-- assigns each row a consecutive number
;WITH DataToUpdate AS
(
    SELECT
        DocumentHeaderId,
        DocumentNumber,
        NewDocNum = ROW_NUMBER() OVER(ORDER BY [Date])
    FROM
        Accounting.DocumentHeader
    WHERE
        FinancialPeriodFK = @FinancialPeriodFK
        AND Date >= @FromDate
        AND Date <= @ToDate
)
-- update the base table to make use of that new document number 
UPDATE dh
SET dh.DocumentNumber = dtu.NewDocNum
FROM Accounting.DocumentHeader dh
INNER JOIN DataToUpdate dtu ON dh.DocumentHeaderId = dtu.DocumentHeaderId

那应该 明显地 加快处理时间!