SQL Server 2005表变量更新问题

Question

我一直在阅读表变量和临时表之间的差异，并偶然发现了表变量的以下问题。我没有看到我追求的文章中提到的这个问题。

我通过XML数据类型传递一系列PK，并在两个临时表结构中成功创建记录。当我尝试更新临时表中的其他字段时，表变量失败，但临时表没有更新语句的问题。需要做些什么？我想利用Table Variables承诺的速度提升......

以下是SP片段和结果：

CREATE PROCEDURE ExpenseReport_AssignApprover
(
    @ExpenseReportIDs       XML
)
AS


DECLARE     @ERTableVariable        TABLE   (   ExpenseReportID             INT,
                                                ExpenseReportProjectID      INT,
                                                ApproverID                  INT)


CREATE TABLE #ERTempTable
(
    ExpenseReportID             INT,
    ExpenseReportProjectID      INT,
    ApproverID                  INT
)

INSERT INTO @ERTableVariable (ExpenseReportID)
SELECT ParamValues.ID.value('.','VARCHAR(20)')
FROM @ExpenseReportIDs.nodes('/Root/ExpenseReportID') as ParamValues(ID)

INSERT INTO #ERTempTable (ExpenseReportID)
SELECT ParamValues.ID.value('.','VARCHAR(20)')
FROM @ExpenseReportIDs.nodes('/Root/ExpenseReportID') as ParamValues(ID)

UPDATE          #ERTempTable
SET             ExpenseReportProjectID = (  SELECT TOP 1 ExpenseReportProjectID 
                                                FROM ExpenseReportItem 
                                                WHERE(ExpenseReportID = #ERTempTable.ExpenseReportID))

UPDATE          @ERTableVariable
SET             ExpenseReportProjectID = (  SELECT TOP 1 ExpenseReportProjectID 
                                                FROM ExpenseReportItem 
                                                WHERE(ExpenseReportID = @ERTableVariable.ExpenseReportID))

上次更新语句时出错： 必须声明标量变量“@ERTableVariable”。

当上次更新被注释掉时，ExpenseReportProjectID在#ERTempTable中更新：

Answer 1

当我在上次更新中对表var参考进行文字化时，快速测试有效：

UPDATE @ERTableVariable
    SET ExpenseReportProjectID = (      
        SELECT TOP 1 ExpenseReportProjectID
        FROM ExpenseReportItem 
        WHERE ExpenseReportID = [@ERTableVariable].ExpenseReportID
    )

您还可以使用'update from'：

UPDATE er SET 
    ExpenseReportProjectID = ExpenseReportItem.ExpenseReportProjectID
FROM @ERTableVariable er
INNER JOIN ExpenseReportItem ON 
    ExpenseReportItem.ExpenseReportID = er.ExpenseReportID

连接可能会返回多行，但只有一行会“粘住”。像'TOP 1'那样的非确定性更新。

Answer 2

试试这个：

CREATE PROCEDURE ExpenseReport_AssignApprover
(
        @ExpenseReportIDs               XML
)
AS BEGIN


DECLARE         @ERTableVariable                TABLE   (       ExpenseReportID                         INT,
                                                                                                ExpenseReportProjectID          INT,
                                                                                                ApproverID                                      INT)


CREATE TABLE #ERTempTable
(
        ExpenseReportID                         INT,
        ExpenseReportProjectID          INT,
        ApproverID                                      INT
)

INSERT INTO @ERTableVariable (ExpenseReportID)
SELECT ParamValues.ID.value('.','VARCHAR(20)')
FROM @ExpenseReportIDs.nodes('/Root/ExpenseReportID') as ParamValues(ID)

INSERT INTO #ERTempTable (ExpenseReportID)
SELECT ParamValues.ID.value('.','VARCHAR(20)')
FROM @ExpenseReportIDs.nodes('/Root/ExpenseReportID') as ParamValues(ID)

UPDATE                  #ERTempTable
SET                             ExpenseReportProjectID = (      SELECT TOP 1 ExpenseReportProjectID 
                                                                                                FROM ExpenseReportItem 
                                                                                                WHERE(ExpenseReportID = #ERTempTable.ExpenseReportID))

UPDATE                  @ERTableVariable
SET                             ExpenseReportProjectID = (      SELECT TOP 1 ExpenseReportProjectID 
                                                                                                FROM ExpenseReportItem 
                                                                                                WHERE(ExpenseReportID = @ERTableVariable.ExpenseReportID))

END