Update only in case where its not null

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How do I UPDATE from a SELECT in SQL Server? 27 answers

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您可以使用此查询来实现您的约束。

Update ExpressMarketCheck set Barcode = (select barcode from ExpressMarket where barcode IS NOT NULL)

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mySQL具有IFNULL功能，所以你可以这样做：

UPDATE your_table_name
SET your_column_name= "data",
scan_created_date = ISNULL( your_column_name, "data" )
WHERE id = X

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I think you want a join :

update emc
    set Barcode = em.barcode, 
        Name = em.name,
        price= em.price
     from ExpressMarketCheck emc join
          expressmarket em
          on emc.?? = em.??;

I cannot tell from your question what columns should be used for the join . The ?? are placeholders.

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