如何使用 Amazon Redshift 中的临时表列更新现有表中的列？答案

【问题标题】：How to update columns in existing table by using temporary table columns in Amazon Redshift?如何使用 Amazon Redshift 中的临时表列更新现有表中的列？
【发布时间】：2021-05-07 05:05:22
【问题描述】：

以下代码是用 SQL 开发的，用于更新目标表列。有人可以帮我在 redshift 中重写下面的查询，因为我试图在亚马逊 redshift 上执行相同的查询，它给出的错误如下：

亚马逊无效操作：关系“c”不存在；

With TempTable As
(
        SELECT   Left('abcdefghijk',len(TerritoryName)/3) +  Substring(TerritoryName,len(TerritoryName)-len(TerritoryName)/3-len(TerritoryName)/3+1,len(TerritoryName)-len(TerritoryName)/3-len(TerritoryName)/3) + Right('ijklmnopqrstuv',len(TerritoryName)/3) As Masked_TerritoryName
                ,Left('abcdefghijk',len(DistrictName)/3) +  Substring(DistrictName,len(DistrictName)-len(DistrictName)/3-len(DistrictName)/3+1,len(DistrictName)-len(DistrictName)/3-len(DistrictName)/3) + Right('ijklmnopqrstuv',len(DistrictName)/3) As Masked_DistrictName
                ,Left('abcdefghijk',len(RegionName)/3) +  Substring(RegionName,len(RegionName)-len(RegionName)/3-len(RegionName)/3+1,len(RegionName)-len(RegionName)/3-len(RegionName)/3) + Right('ijklmnopqrstuv',len(RegionName)/3) As Masked_RegionName
                ,Left('abcdefghijk',len(RSMTerritoryName)/3) +  Substring(RSMTerritoryName,len(RSMTerritoryName)-len(RSMTerritoryName)/3-len(RSMTerritoryName)/3+1,len(RSMTerritoryName)-len(RSMTerritoryName)/3-len(RSMTerritoryName)/3) + Right('ijklmnopqrstuv',len(RSMTerritoryName)/3) As Masked_RSMTerritoryName
                ,Left('abcdefghijk',len(CCAName)/3) +  Substring(CCAName,len(CCAName)-len(CCAName)/3-len(CCAName)/3+1,len(CCAName)-len(CCAName)/3-len(CCAName)/3) + Right('ijklmnopqrstuv',len(CCAName)/3) As Masked_CCAName
                ,Left('abcdefghijk',len(LCAName)/3) +  Substring(LCAName,len(LCAName)-len(LCAName)/3-len(LCAName)/3+1,len(LCAName)-len(LCAName)/3-len(LCAName)/3) + Right('ijklmnopqrstuv',len(LCAName)/3) As Masked_LCAName
                ,Left('abcdefghijk',len(TMComp)/3) +  Substring(TMComp,len(TMComp)-len(TMComp)/3-len(TMComp)/3+1,len(TMComp)-len(TMComp)/3-len(TMComp)/3) + Right('ijklmnopqrstuv',len(TMComp)/3) As Masked_TMComp
                ,Left('abcdefghijk',len(ASMTerritoryName)/3) +  Substring(ASMTerritoryName,len(ASMTerritoryName)-len(ASMTerritoryName)/3-len(ASMTerritoryName)/3+1,len(ASMTerritoryName)-len(ASMTerritoryName)/3-len(ASMTerritoryName)/3) + Right('ijklmnopqrstuv',len(ASMTerritoryName)/3) As Masked_ASMTerritoryName
                ,TerritoryCode      
        FROM TargetTable
)
    Update C
    Set      C.TerritoryName = N.Masked_TerritoryName
            ,C.DistrictName = N.Masked_DistrictName
            ,C.RegionName = N.Masked_RegionName
            ,C.RSMTerritoryName = N.Masked_RSMTerritoryName
            ,C.CCAName = N.Masked_CCAName
            ,C.LCAName = N.Masked_LCAName
            ,C.TMComp = N.Masked_TMComp
            ,C.ASMTerritoryName = N.Masked_ASMTerritoryName
    From TargetTable C
        Inner Join TempTable N ON C.TerritoryCode = N.TerritoryCode

【问题讨论】：

请只标记一个 RDBMS

标签： sql-update amazon-redshift

【解决方案1】：

我不相信您可以只为目标表使用别名。您有“...更新 C ...”，我希望您需要“...更新 TargetTable ...”或“...更新 TargetTable C ...”。

您也不需要在 FROM 子句中列出 TargetTable，因为这是假定的。您的加入条件成为条件。因此，您的查询将如下所示：

With TempTable As
(
        SELECT ...
        FROM TargetTable
)
Update TargetTable C
    Set      ...
From TempTable N
Where C.TerritoryCode = N.TerritoryCode

【讨论】：