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smile
Starting Member
22 Posts |
 Posted - 2009-04-05 : 18:46:08
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| Hello!I was using the Northwind database and I don't get few queries:1)Retrieve the names of the products that were never ordered.Which of the two queries is the right one? I suppose that it's the first?select productname from products where productid not in (select productid from orderdetails)select productname from products p left join orderdetails od on p.productid=od.productid--where orderid is null2) Retrieve the number of the suppliers that have the same region like the client.select c.region,count(supplierid) from suppliers s join customers c on s.region=c.regiongroup by c.regionselect c.region,count(s.supplierid) from suppliers s join products p on s.supplierid=p.supplieridjoin orderdetails od on p.productid=od.productid join orders o on o.orderid=od.orderid join customers c on o.customerid=c.customeridwhere s.region=c.regiongroup by c.regionAgain I suppose that the first one is the right one?Thanks a lot! |
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bklr
Master Smack Fu Yak Hacker
1693 Posts |
Posted - 2009-04-06 : 00:49:47
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| in first case u can use any one of it prefer 2 one1.select productname from products where productid not in (select productid from orderdetails)2.select productname from products p left join orderdetails od on p.productid=od.productidwhere productidis null3.select productname from products p where not exists(select * from orderdetails where productid = p.productid ) |
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few queries