根据 文档 Azure SQL 数据仓库确实支持 UPDATE，但不支持 FROM 子句中的 ANSI 连接.您可以使用 CTAS 来解决.简单的两表更新:

As per the documentation Azure SQL Data Warehouse does support UPDATE but does not support ANSI joins in the FROM clause. You can use CTAS to work around. Simple two-table update:

UPDATE dbo.FactTable
SET
   Value1 = CASE WHEN stage.Value1 > dbo.FactTable.Value1 THEN stage.Value1 ELSE dbo.FactTable.Value1 END
FROM dbo.StageTable AS stage
WHERE dbo.FactTable.Id1 = stage.Id1 
  AND dbo.FactTable.Id2 = stage.Id2;

更复杂的 CTAS 示例，从 主更新文档页面:

More complex example with CTAS, copied wholesale from the main UPDATE documentation page:

-- Create an interim table
CREATE TABLE CTAS_acs
WITH (DISTRIBUTION = ROUND_ROBIN)
AS
SELECT  ISNULL(CAST([EnglishProductCategoryName] AS NVARCHAR(50)),0)    AS [EnglishProductCategoryName]
,       ISNULL(CAST([CalendarYear] AS SMALLINT),0)                      AS [CalendarYear]
,       ISNULL(CAST(SUM([SalesAmount]) AS MONEY),0)                     AS [TotalSalesAmount]
FROM    [dbo].[FactInternetSales]       AS s
JOIN    [dbo].[DimDate]                 AS d    ON s.[OrderDateKey]             = d.[DateKey]
JOIN    [dbo].[DimProduct]              AS p    ON s.[ProductKey]               = p.[ProductKey]
JOIN    [dbo].[DimProductSubCategory]   AS u    ON p.[ProductSubcategoryKey]    = u.[ProductSubcategoryKey]
JOIN    [dbo].[DimProductCategory]      AS c    ON u.[ProductCategoryKey]       = c.[ProductCategoryKey]
WHERE   [CalendarYear] = 2004
GROUP BY
        [EnglishProductCategoryName]
,       [CalendarYear]
;

-- Use an implicit join to perform the update
UPDATE  AnnualCategorySales
SET     AnnualCategorySales.TotalSalesAmount = CTAS_ACS.TotalSalesAmount
FROM    CTAS_acs
WHERE   CTAS_acs.[EnglishProductCategoryName] = AnnualCategorySales.[EnglishProductCategoryName]
AND     CTAS_acs.[CalendarYear]               = AnnualCategorySales.[CalendarYear]
;

--Drop the interim table
DROP TABLE CTAS_acs
;