Quick SQL code help dealing with NULLS 1

[grippy]

UPDATE ProductVariant
SET Length = (SELECT Table1.Length
FROM Table1
WHERE ProductVariant.Sku = Table1.Sku)

I keep getting this NULL error code but cant figure it out. There are no nulls in Table1 is there something I should add to the code to make this work? Thank you.

Msg 515, Level 16, State 2, Line 1
Cannot insert the value NULL into column 'Length', table 'database.dbo.ProductVariant'; column does not allow nulls. UPDATE fails.
The statement has been terminated

 

[r937]

there's at least one row in Table1 that doesn't have a matching sku, and in that case the subquery returns NULL

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[grippy]

Oh ok that is why then because there is a lot of data in table1 but not all of the skus exist in ProductVariant table. What would I need to change on my code to counteract that ? Thank you for your help.

 

[r937]

UPDATE ProductVariant
   SET Length = t1.Length
  FROM ProductVariant pv
INNER
  JOIN Table1 t1
    ON t1.Sku = pv.Sku

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