100分：大抛卖啦 走过路过不要错过，一个sp问题
有个SP执行要化十多分钟，代码如下：
IF   EXISTS   (SELECT   *   FROM   dbo.sysobjects   WHERE   id   =   OBJECT_ID(N '[dbo].[usp_StatisticsTotalPurchase] ')   AND   OBJECTPROPERTY(id,   N 'IsProcedure ')   =   1)
DROP   PROC   [dbo].[usp_StatisticsTotalPurchase]
GO

CREATE   PROC   [dbo].[usp_StatisticsTotalPurchase]
@Reference   INT,
@BeginDate   DATETIME,
@EndDate   DATETIME,
@ErrorNumber   INT   OUTPUT,
@ErrorInfo   NVARCHAR(200)   OUTPUT
AS
SET   NOCOUNT   ON;

DECLARE   @Profit   MONEY
,   @RefStandardCost   MONEY
,   @PartID   NVARCHAR(60)
,   @Mode   NVARCHAR(10)
,   @Date   DATETIME
,   @YearMonth   NVARCHAR(6);

--得到利润率
SELECT   @Profit   =   Profit
FROM   dbo.Profit
WHERE   Active   =   1;

IF   @Profit   IS   NULL
BEGIN
SELECT   @ErrorNumber   =   110,   @ErrorInfo   =   N 'Profit   data   not   set. ';
SET   NOCOUNT   OFF;
RETURN   CAST(0   AS   BIT);
END;

--确定统计的部件
DECLARE   @Parts   TABLE
(
PartID   NVARCHAR(60)   COLLATE   Chinese_PRC_CI_AS   NOT   NULL   PRIMARY   KEY,
RefStdCost   MONEY
);

IF   LEN(CAST(@Reference   AS   NVARCHAR))   =   6
INSERT   INTO   @Parts   (PartID)
SELECT   DISTINCT   PartID
FROM   dbo.StandardCost
WHERE   IsPurchased   =   1
AND   YEAR([Date])   *   100   +   MONTH([Date])   <=   @Reference;
ELSE
INSERT   INTO   @Parts   (PartID)
SELECT   DISTINCT   PartID
FROM   dbo.StandardCost
WHERE   IsPurchased   =   1
AND   YEAR([Date])   <=   @Reference;

DELETE   @Parts
FROM   @Parts   p
INNER   JOIN
(
SELECT   PartID
FROM   dbo.StandardCost
GROUP   BY   PartID
HAVING   SUM(Price)   =   0
)   c
ON   p.PartID   =   c.PartID;

DELETE   @Parts
FROM   @Parts   p
WHERE   NOT   EXISTS
(
SELECT   1
FROM   iERP72tech.dbo.POM   pom
INNER   JOIN   iERP72tech.dbo.POI   poi
ON   poi.POI_PurchOrderID   =   pom.POM_PurchOrderID
INNER   JOIN   iERP72tech.dbo.POD   pod
ON   pod.POD_PurchOrderID   =   pom.POM_PurchOrderID
AND   pod.POD_POLineNbr   =   poi.POI_POLineNbr
WHERE   poi.POI_LineNbrTypeCode   =   N 'Item '
AND   pod.POD_POUnitPrice   >   0
AND   pom.POM_PurchOrderDate   > =   @BeginDate
AND   pom.POM_PurchOrderDate   <   DATEADD(DAY,   1,   @EndDate)
AND   poi.POI_ItemID   COLLATE   Chinese_PRC_CI_AS   =   p.PartID
);

IF   NOT   EXISTS   (SELECT   1   FROM   @Parts)
BEGIN
SELECT   @ErrorNumber   =   110,   @ErrorInfo   =   N 'Standard   cost   in   reference   period   not   exists. ';
SET   NOCOUNT &n