[英]SQL query join condition
我有以下關系的數據庫:
Bar(Name, Address, Licence)
Beer(Name,Manufacture)
Drinker(Name,Address)
Frequents(DrinkerName,BarName)
Likes(DrinkerName,BeerName)
Sells(BarName,BeerName,Amount)
Serves(BarName,BeerName)
示例 DDL 語句:
CREATE TABLE `Bar` (
`Name` varchar(255) NOT NULL,
`Address` varchar(255) DEFAULT NULL,
`Licence` varchar(255) DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
INSERT INTO `Bar` (`Name`, `Address`, `Licence`) VALUES
('Deluxe', 'Luxvagen 2', 'Yes'),
('Grace', 'Gracevagen 2', 'Yes'),
('KrogBar', 'Barvagen 2', 'Yes');
CREATE TABLE `Beer` (
`Name` varchar(255) NOT NULL,
`Manufacture` varchar(255) DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
INSERT INTO `Beer` (`Name`, `Manufacture`) VALUES
('Carlsberg', 'Coppers'),
('Heiniken', 'Spendrups'),
('Miller', 'DaMill');
CREATE TABLE `Boor` (
`Name` varchar(255) NOT NULL,
`Age` int(11) DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
CREATE TABLE `Drinker` (
`Name` varchar(255) NOT NULL,
`Address` varchar(255) DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
INSERT INTO `Drinker` (`Name`, `Address`) VALUES
('Alex', 'Överbar 2'),
('Bam', 'Påbar 2'),
('Emil', 'Mittibar 2'),
('Max', 'Ibar 2'),
('Petra', 'Förebar 2'),
('Rebecca', 'Efterbar 2'),
('Sam', 'Underbar 2');
CREATE TABLE `Frequents` (
`DrinkerName` varchar(255) NOT NULL DEFAULT '',
`BarName` varchar(255) NOT NULL DEFAULT ''
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
INSERT INTO `Frequents` (`DrinkerName`, `BarName`) VALUES
('Emil', 'Deluxe'),
('Max', 'Deluxe'),
('Rebecca', 'Deluxe'),
('Alex', 'Grace'),
('Petra', 'Grace'),
('Bam', 'KrogBar'),
('Sam', 'KrogBar');
CREATE TABLE `Likes` (
`DrinkerName` varchar(255) NOT NULL DEFAULT '',
`BeerName` varchar(255) NOT NULL DEFAULT ''
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
INSERT INTO `Likes` (`DrinkerName`, `BeerName`) VALUES
('Bam', 'Carlsberg'),
('Emil', 'Carlsberg'),
('Rebecca', 'Carlsberg'),
('Emil', 'Heiniken'),
('Max', 'Heiniken'),
('Petra', 'Heiniken'),
('Sam', 'Heiniken'),
('Alex', 'Miller');
CREATE TABLE `Sells` (
`BarName` varchar(100) DEFAULT NULL,
`BeerName` varchar(100) DEFAULT NULL,
`Amount` int(11) DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
INSERT INTO `Sells` (`BarName`, `BeerName`, `Amount`) VALUES
('KrogBar', 'Miller', 3),
('KrogBar', 'Carlsberg', 2),
('KrogBar', 'Heiniken', 1),
('Deluxe', 'Heiniken', 1);
CREATE TABLE `Serves` (
`BarName` varchar(255) NOT NULL DEFAULT '',
`BeerName` varchar(255) NOT NULL DEFAULT ''
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
INSERT INTO `Serves` (`BarName`, `BeerName`) VALUES
('Grace', 'Carlsberg'),
('KrogBar', 'Carlsberg'),
('Deluxe', 'Heiniken'),
('Grace', 'Heiniken'),
('KrogBar', 'Heiniken'),
('KrogBar', 'Miller');
我想找到只光顧提供他們喜歡的啤酒的酒吧的飲酒者(假設每個飲酒者至少光顧一個酒吧)。 我怎樣才能構造這樣的查詢? 我知道我必須使用連接和子查詢,我對它們中的任何一個都不陌生,但我的所有實現都沒有產生正確的結果。
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