easy to understand  my sql solution without join or cte
easy my sql solution \n\nselect product_id, product_name from product where product_id not in ( \nselect product_id from sales\nwhere sale_date not between \'20
easy my sql solution \n```\nselect product_id, product_name from product where product_id not in ( \nselect product_id from sales\nwhere sale_date not between \'2019-01-01\' and \'2019-03-31\')\n```
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