Re: SubQueries and IN

[Sebastian Tobias Mendel genannt Mendelsohn]

>>SELECT product_id, name, description, sales.sale_id
>>FROM products LEFT JOIN sales ON products.product_id = sales.product_id
>>WHERE sales.customer_id = 10 AND sales.sale_id IS NULL
> 
> 
> This query should return no rows, because if you retrieve rows where sales.sale_id is
> NULL, customer_id for these rows also will be NULL, not 10.


you are wrong, or do you know the table-structure?
sales.sale_id can be NULL while customer_id can be 10 !

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Sebastian Mendel

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