paulpol87
Starting Member
7 Posts |
Posted - 2012-02-03 : 10:11:25
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The database scheme consists of four tables:Product(maker, model, type)PC(code, model, speed, ram, hd, cd, price)Laptop(code, model, speed, ram, hd, screen, price)Printer(code, model, color, type, price)The table "Product" includes information about the maker, model number, and type ('PC', 'Laptop', or 'Printer'). It is assumed that model numbers in the Product table are unique for all the makers and product types. Each PC uniquely specifying by a code in the table "PC" is characterized by model (foreign key referencing to Product table), speed (of the processor in MHz), total amount of RAM - ram (in Mb), hard disk drive capacity - hd (in Gb), CD ROM speed - cd (for example, '4x'), and the price. The table "Laptop" is similar to that one of PCs except for the CD ROM speed, which is replaced by the screen size - screen (in inches). For each printer in the table "Printer" it is told whether the printer is color or not (color attribute is 'y' for color printers; otherwise it is 'n'), printer type (laser, jet, or matrix), and the price.Find the printer makers which also produce PCs with the lowest RAM and the highest-speed processor among PCs with the lowest RAM. Result set: maker. My query:select maker from (select maker, model from product where type in ('printer','pc')) as a where model in (select model from (select model, speed, min(ram) as ram from pc where speed=(select max(speed) from pc) group by speed, model) as a)Result:Incorrect.* Wrong number of records (less by 1)The results of your query:makerACorrect query: makerAEI really need your help!! I've been trying since yesterday to sort it out... |
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visakh16
Very Important crosS Applying yaK Herder
52326 Posts |
Posted - 2012-02-03 : 10:54:45
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[code]SELECT p.maker FROM(SELECT *,DENSE_RANK() OVER (ORDER BY ram ASC,speed DESC) AS RnkFROM Product pINNER JOIN (SELECT maker FROM Product WHERE type IN ('PC','printer') GROUP BY maker HAVING COUNT(DISTINCT type)=2 )p1ON p1.maker = p.makerINNER JOIN PC ON PC.model = p.model)tWHERE Rnk=1[/code]------------------------------------------------------------------------------------------------------SQL Server MVPhttp://visakhm.blogspot.com/ |
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