Question

我有以下更新声明：

UPDATE D     
  SET D.Xtra1 = CASE 
                  when ExtendedProperties.PropertyName="Transmittal Number" then ExtendedProperties.PropertyValue 
                  else NULL 
                END, 
      D.Xtra2 = CASE
                  when (ExtendedProperties.PropertyName="File Identification") then ExtendedProperties.PropertyValue 
                  else NULL 
                END, 
      D.Xtra3 = CASE
                  when (ExtendedProperties.PropertyName="File Owner") then ExtendedProperties.PropertyValue 
                  else NULL 
                END, 
      D.Xtra4 =  case 
                  when (ExtendedProperties.PropertyName="Dept File Cabinet") then     ExtendedProperties.PropertyValue 
                  else NULL 
                END ,
      D.Xtra5 = case 
                 when (ExtendedProperties.PropertyName="Record Storage Box Number") then ExtendedProperties.PropertyValue 
                 else NULL 
                END ,
      D.Xtra6 = case 
                 when (ExtendedProperties.PropertyName="ImportCode") then extendedProperties.PropertyValue 
                 else NULL 
                END , 
      D.Xtra7 = case 
                 when (ExtendedProperties.PropertyName="ImageKey") then extendedProperties.PropertyValue 
                else NULL 
                END , 
      D.Xtra8 =  case 
                 when (ExtendedProperties.PropertyName="Boundary") then ExtendedProperties.PropertyValue 
                 else NULL 
                END ,
      D.Xtra9 = case 
                 when (ExtendedProperties.PropertyName="Offset") then ExtendedProperties.PropertyValue 
                 else NULL 
                END ,
      D.Xtra10 = case 
                 when (ExtendedProperties.PropertyName="UniqueFilename") then ExtendedProperties.PropertyValue 
                 else NULL 
                END

来自ExtendedProperties内连接数据D的

在D.ItemID = ExtendedProperties.ItemID

上

更新无效，我还没弄清楚原因。

如果我执行单个直接更新语句，它允许我写入该字段。如果我只选择其中一个case语句，它会正确绘制字段。

任何想法？

Answer 1

您的问题是您在此处转置表格。源表具有项目的 N 行（ItemId，PropertyName和PropertyValue），但目标表有一行，其中 N 列（Xtra1 ... Xtra10）。

左连接可用于将源从行转置为列，并且所有值可以同时使用，而不是按顺序。

UPDATE
  data 
SET
  data.Xtra1  = ep01.PropertyValue, 
  data.Xtra2  = ep02.PropertyValue, 
  data.Xtra3  = ep03.PropertyValue, 
  data.Xtra4  = ep04.PropertyValue,
  data.Xtra5  = ep05.PropertyValue,
  data.Xtra6  = ep06.PropertyValue,
  data.Xtra7  = ep07.PropertyValue,
  data.Xtra8  = ep09.PropertyValue,
  data.Xtra9  = ep09.PropertyValue,
  data.Xtra10 = ep10.PropertyValue
FROM
  data
  LEFT JOIN ExtendedProperties ep01 ON data.ItemID = ep01.ItemID AND ep01.PropertyName = 'Transmittal Number'
  LEFT JOIN ExtendedProperties ep02 ON data.ItemID = ep02.ItemID AND ep02.PropertyName = 'File Identification'
  LEFT JOIN ExtendedProperties ep03 ON data.ItemID = ep03.ItemID AND ep03.PropertyName = 'File Owner'
  LEFT JOIN ExtendedProperties ep04 ON data.ItemID = ep04.ItemID AND ep04.PropertyName = 'Dept File Cabinet'
  LEFT JOIN ExtendedProperties ep05 ON data.ItemID = ep05.ItemID AND ep05.PropertyName = 'Record Storage Box Number'
  LEFT JOIN ExtendedProperties ep06 ON data.ItemID = ep06.ItemID AND ep06.PropertyName = 'ImportCode'
  LEFT JOIN ExtendedProperties ep07 ON data.ItemID = ep07.ItemID AND ep07.PropertyName = 'ImageKey'
  LEFT JOIN ExtendedProperties ep08 ON data.ItemID = ep08.ItemID AND ep08.PropertyName = 'Boundary'
  LEFT JOIN ExtendedProperties ep09 ON data.ItemID = ep09.ItemID AND ep09.PropertyName = 'Offset'
  LEFT JOIN ExtendedProperties ep10 ON data.ItemID = ep10.ItemID AND ep10.PropertyName = 'UniqueFilename'

如果你有很多记录，就有一个超过(ItemID, PropertyName)的联合收购指数，以便顺利运作。

编辑：或者，你可以这样做：

UPDATE
  data 
SET
  data.Xtra1  = (SELECT PropertyValue FROM ExtendedProperties WHERE ItemID = data.ItemID AND PropertyName = 'Transmittal Number'), 
  data.Xtra2  = (SELECT PropertyValue FROM ExtendedProperties WHERE ItemID = data.ItemID AND PropertyName = 'File Identification'), 
  data.Xtra3  = (SELECT PropertyValue FROM ExtendedProperties WHERE ItemID = data.ItemID AND PropertyName = 'File Owner'), 
  data.Xtra4  = (SELECT PropertyValue FROM ExtendedProperties WHERE ItemID = data.ItemID AND PropertyName = 'Dept File Cabinet'),
  data.Xtra5  = (SELECT PropertyValue FROM ExtendedProperties WHERE ItemID = data.ItemID AND PropertyName = 'Record Storage Box Number'),
  data.Xtra6  = (SELECT PropertyValue FROM ExtendedProperties WHERE ItemID = data.ItemID AND PropertyName = 'ImportCode'),
  data.Xtra7  = (SELECT PropertyValue FROM ExtendedProperties WHERE ItemID = data.ItemID AND PropertyName = 'ImageKey'),
  data.Xtra8  = (SELECT PropertyValue FROM ExtendedProperties WHERE ItemID = data.ItemID AND PropertyName = 'Boundary'),
  data.Xtra9  = (SELECT PropertyValue FROM ExtendedProperties WHERE ItemID = data.ItemID AND PropertyName = 'Offset'),
  data.Xtra10 = (SELECT PropertyValue FROM ExtendedProperties WHERE ItemID = data.ItemID AND PropertyName = 'UniqueFilename')

代码少，可能更容易理解，也许不那么快（这是猜测）。

Answer 2

您需要在FROM子句中包含data表

from  data
join ExtendedProperties on data.ItemID = ExtendedProperties.ItemID

tsql：用case语句更新表 - 什么错了？

2 个答案: