ネストされたサブクエリを理解するには？

Question

私はサブクエリを理解しようとしています。以前の問題を理解していると思っていましたが、ネストされたサブクエリを理解したいと思っています。

は、私はこのような出力を作るしようとしています：GPS、シートヒーター、およびAWD：私はこれらがこれらの説明を通じてます見つけようとしてAF

Model        Year 
--------------------------- ------------ 
Grand Caravan      2010 
Q70         2015 

方法。

現在、選択されている行がありません。示すように

私の文は次のとおりです。

SELECT t1.MODELNAME AS Model, t2.VEHICLEYEAR AS Year 
FROM TBLMODEL t1 
FULL JOIN TBLVEHICLE t2 ON t1.MODELID = t2.MODELID 
FULL JOIN TBLOPTIONDETAIL t3 ON t2.VEHICLEID = t3.VEHICLEID 
FULL JOIN TBLOPTION t4 ON t3.OPTIONID = t4.OPTIONID 
WHERE t4.OPTIONDESC IN 
(
    SELECT OPTIONDESC 
    FROM TBLOPTION 
    WHERE OPTIONDESC = 'GPS' AND OPTIONDESC = 
    (
    SELECT OPTIONDESC 
    FROM TBLOPTION 
    WHERE OPTIONDESC = 'Heated Seats' 
) 
); 

それが対応するファイルへ：

DROP TABLE tblOptionDetail; 
DROP TABLE tblOption; 
DROP TABLE tblVehicle; 
DROP TABLE tblModel; 
DROP TABLE tblBrand; 
DROP TABLE tblManufacture; 


CREATE TABLE tblManufacture 
(
ManufactureID NUMBER(38) PRIMARY KEY, 
ManufactureName CHAR(40) 
); 

CREATE TABLE tblBrand 
(
BrandID NUMBER(38) PRIMARY KEY, 
ManufactureID NUMBER(38), 
BrandName CHAR(40), 
FOREIGN KEY (ManufactureID) REFERENCES tblManufacture(ManufactureID) 
); 

CREATE TABLE tblModel 
(
ModelID NUMBER(38) PRIMARY KEY, 
BrandID NUMBER(38), 
ModelName CHAR(40), 
FOREIGN KEY (BrandID) REFERENCES tblBrand(BrandID) 
); 

CREATE TABLE tblVehicle 
(
VehicleID NUMBER(38) PRIMARY KEY, 
ModelID NUMBER(38), 
VehicleYear NUMBER(38) CHECK (VehicleYear BETWEEN 1900 and 3000), 
VehicleKM NUMBER(38) CHECK (VehicleKM BETWEEN 0 and 100000000), 
VehiclePrice NUMBER(38) CONSTRAINT carprice CHECK (VehiclePrice BETWEEN 0 and 1000000), 
FOREIGN KEY (ModelID) REFERENCES tblModel(ModelID) 
); 

CREATE TABLE tblOption 
(
OptionID NUMBER(38) PRIMARY KEY, 
OptionDesc CHAR(40) 
); 

CREATE TABLE tblOptionDetail 
(
OptionID NUMBER(38), 
VehicleID NUMBER(38), 
PRIMARY KEY (OptionID, VehicleID), 
FOREIGN KEY (OptionID) REFERENCES tblOption(OptionID), 
FOREIGN KEY (VehicleID) REFERENCES tblVehicle(VehicleID) 
); 


-- populate the Manufacture table 

INSERT ALL 
INTO tblManufacture (ManufactureID, ManufactureName) VALUES (1,'Chrysler Corp.') 
INTO tblManufacture (ManufactureID, ManufactureName) VALUES(2,'General Motors') 
INTO tblManufacture (ManufactureID, ManufactureName) VALUES(3,'Ford Motor Company') 
INTO tblManufacture (ManufactureID, ManufactureName) VALUES(4,'Toyota') 
INTO tblManufacture (ManufactureID, ManufactureName) VALUES (5,'Honda') 
INTO tblManufacture (ManufactureID, ManufactureName) VALUES (6,'Nisan') 
SELECT * FROM dual; 

-- populate the Brand table 

INSERT ALL 
INTO tblBrand (BrandID, ManufactureID, BrandName) VALUES (1,1, 'Chrysler') 
INTO tblBrand (BrandID, ManufactureID, BrandName) VALUES (2,1, 'Dodge') 
INTO tblBrand (BrandID, ManufactureID, BrandName) VALUES (3,1, 'Jeep') 
INTO tblBrand (BrandID, ManufactureID, BrandName) VALUES (4,2, 'Chevrolet') 
INTO tblBrand (BrandID, ManufactureID, BrandName) VALUES (5,2, 'Buick') 
INTO tblBrand (BrandID, ManufactureID, BrandName) VALUES (6,2, 'Cadillac') 
INTO tblBrand (BrandID, ManufactureID, BrandName) VALUES (7,2, 'GMC') 
INTO tblBrand (BrandID, ManufactureID, BrandName) VALUES (8,4, 'Toyota') 
INTO tblBrand (BrandID, ManufactureID, BrandName) VALUES (9,6, 'Nissan') 
INTO tblBrand (BrandID, ManufactureID, BrandName) VALUES (10,6,'Infiniti') 
SELECT * FROM dual; 

-- populate the Model table 

INSERT ALL 
INTO tblModel (ModelID, BrandID, ModelName) VALUES (1,1, '200') 
INTO tblModel (ModelID, BrandID, ModelName) VALUES (2,1, '200 Convertible') 
INTO tblModel (ModelID, BrandID, ModelName) VALUES (3,1, '300') 
INTO tblModel (ModelID, BrandID, ModelName) VALUES (4,1, 'Town'||' & '||'Country') 
INTO tblModel (ModelID, BrandID, ModelName) VALUES (5,2, 'Durango') 
INTO tblModel (ModelID, BrandID, ModelName) VALUES (6,2, 'Avenger') 
INTO tblModel (ModelID, BrandID, ModelName) VALUES (7,2, 'Challenger') 
INTO tblModel (ModelID, BrandID, ModelName) VALUES (8,2, 'Charger') 
INTO tblModel (ModelID, BrandID, ModelName) VALUES (9,2, 'Caliber') 
INTO tblModel (ModelID, BrandID, ModelName) VALUES (10,2, 'Grand Caravan') 
INTO tblModel (ModelID, BrandID, ModelName) VALUES (11,2, 'Journey') 
INTO tblModel (ModelID, BrandID, ModelName) VALUES (12,4, 'Sonic') 
INTO tblModel (ModelID, BrandID, ModelName) VALUES (13,4, 'Cruze') 
INTO tblModel (ModelID, BrandID, ModelName) VALUES (14,4, 'Orlando') 
INTO tblModel (ModelID, BrandID, ModelName) VALUES (15,4, 'Colorado') 
INTO tblModel (ModelID, BrandID, ModelName) VALUES (16,4, 'Malibu') 
INTO tblModel (ModelID, BrandID, ModelName) VALUES (17,8, '4Runner') 
INTO tblModel (ModelID, BrandID, ModelName) VALUES (18,8, 'Prius') 
INTO tblModel (ModelID, BrandID, ModelName) VALUES (19,8, 'Camry') 
INTO tblModel (ModelID, BrandID, ModelName) VALUES (20,8, 'Corolla') 
INTO tblModel (ModelID, BrandID, ModelName) VALUES (21,9,'Rogue SL') 
INTO tblModel (ModelID, BrandID, ModelName) VALUES (22,9, 'Versa Note') 
INTO tblModel (ModelID, BrandID, ModelName) VALUES (23,9, 'Pathfinder') 
INTO tblModel (ModelID, BrandID, ModelName) VALUES (24,9, 'Altima') 
INTO tblModel (ModelID, BrandID, ModelName) VALUES (25,10, 'Q70') 
INTO tblModel (ModelID, BrandID, ModelName) VALUES (26,10, 'Q50') 
INTO tblModel (ModelID, BrandID, ModelName) VALUES (27,10, 'Q60') 
INTO tblModel (ModelID, BrandID, ModelName) VALUES (28,10, 'EX37') 
SELECT * FROM dual; 

-- populate Option table 

INSERT ALL 
INTO tblOption (OptionID,OptionDesc) VALUES (1,'Power locks') 
INTO tblOption (OptionID,OptionDesc) VALUES (2,'Power windows') 
INTO tblOption (OptionID,OptionDesc) VALUES (3,'Air conditioning') 
INTO tblOption (OptionID,OptionDesc) VALUES (4,'Heated mirrors') 
INTO tblOption (OptionID,OptionDesc) VALUES (5,'Remote keyless entry') 
INTO tblOption (OptionID,OptionDesc) VALUES (6,'CD Player') 
INTO tblOption (OptionID,OptionDesc) VALUES (7,'GPS') 
INTO tblOption (OptionID,OptionDesc) VALUES (8,'In-dash DVD player') 
INTO tblOption (OptionID,OptionDesc) VALUES (9,'Overhead DVD player') 
INTO tblOption (OptionID,OptionDesc) VALUES (10,'Satellite radio') 
INTO tblOption (OptionID,OptionDesc) VALUES (11,'MP3 player') 
INTO tblOption (OptionID,OptionDesc) VALUES (12,'Antilock braking system') 
INTO tblOption (OptionID,OptionDesc) VALUES (13,'Electronic stability system') 
INTO tblOption (OptionID,OptionDesc) VALUES (14,'Traction control') 
INTO tblOption (OptionID,OptionDesc) VALUES (15,'Cruise control') 
INTO tblOption (OptionID,OptionDesc) VALUES (16,'Intelligent cruise control') 
INTO tblOption (OptionID,OptionDesc) VALUES (17,'Parking assist system') 
INTO tblOption (OptionID,OptionDesc) VALUES (18,'Xenon headlights') 
INTO tblOption (OptionID,OptionDesc) VALUES (19,'Aluminum rims') 
INTO tblOption (OptionID,OptionDesc) VALUES (20,'AWD') 
INTO tblOption (OptionID,OptionDesc) VALUES (21,'Convertable') 
INTO tblOption (OptionID,OptionDesc) VALUES (22,'Heated Seats') 
SELECT * FROM dual; 

-- populate Vehicle table 

INSERT ALL 
INTO tblVehicle (VehicleID,ModelID, VehicleYear, VehicleKM, VehiclePrice) VALUES (1,10, 2010, 45000, 18000) 
INTO tblVehicle (VehicleID,ModelID, VehicleYear, VehicleKM, VehiclePrice) VALUES (2,10, 2010, 65420, 17500) 
INTO tblVehicle (VehicleID,ModelID, VehicleYear, VehicleKM, VehiclePrice) VALUES (3,16, 2004, 143900, 3200) 
INTO tblVehicle (VehicleID,ModelID, VehicleYear, VehicleKM, VehiclePrice) VALUES (4,11, 2010, 38900, 14500) 
INTO tblVehicle (VehicleID,ModelID, VehicleYear, VehicleKM, VehiclePrice) VALUES (5,27,2014,17250,45999) 
INTO tblVehicle (VehicleID,ModelID, VehicleYear, VehicleKM, VehiclePrice) VALUES (6,25,2015,2900,62300) 
INTO tblVehicle (VehicleID,ModelID, VehicleYear, VehicleKM, VehiclePrice) VALUES (7,17,2010,87900,19800) 
SELECT * FROM dual; 

-- populate OptionDetail table 

INSERT ALL 
INTO tblOptionDetail (OptionID, VehicleID) VALUES (2, 2) 
INTO tblOptionDetail (OptionID, VehicleID) VALUES (1, 2) 
INTO tblOptionDetail (OptionID, VehicleID) VALUES (3, 2) 
INTO tblOptionDetail (OptionID, VehicleID) VALUES (5, 2) 
INTO tblOptionDetail (OptionID, VehicleID) VALUES (6, 2) 
INTO tblOptionDetail (OptionID, VehicleID) VALUES (7, 2) 
INTO tblOptionDetail (OptionID, VehicleID) VALUES (8, 2) 
INTO tblOptionDetail (OptionID, VehicleID) VALUES (11, 2) 
INTO tblOptionDetail (OptionID, VehicleID) VALUES (12, 2) 
INTO tblOptionDetail (OptionID, VehicleID) VALUES (14, 2) 
INTO tblOptionDetail (OptionID, VehicleID) VALUES (15, 2) 
INTO tblOptionDetail (OptionID, VehicleID) VALUES (19, 2) 
INTO tblOptionDetail (OptionID, VehicleID) VALUES (2, 1) 
INTO tblOptionDetail (OptionID, VehicleID) VALUES (1, 1) 
INTO tblOptionDetail (OptionID, VehicleID) VALUES (3, 1) 
INTO tblOptionDetail (OptionID, VehicleID) VALUES (6, 1) 
INTO tblOptionDetail (OptionID, VehicleID) VALUES (12, 1) 
INTO tblOptionDetail (OptionID, VehicleID) VALUES (14, 1) 
INTO tblOptionDetail (OptionID, VehicleID) VALUES (15, 1) 
INTO tblOptionDetail (OptionID, VehicleID) VALUES (19, 1) 
INTO tblOptionDetail (OptionID, VehicleID) VALUES (2, 3) 
INTO tblOptionDetail (OptionID, VehicleID) VALUES (1, 3) 
INTO tblOptionDetail (OptionID, VehicleID) VALUES (3, 3) 
INTO tblOptionDetail (OptionID, VehicleID) VALUES (6, 3) 
INTO tblOptionDetail (OptionID, VehicleID) VALUES (12, 3) 
INTO tblOptionDetail (OptionID, VehicleID) VALUES (14, 3) 
INTO tblOptionDetail (OptionID, VehicleID) VALUES (15, 3) 
INTO tblOptionDetail (OptionID, VehicleID) VALUES (19, 3) 
INTO tblOptionDetail (OptionID, VehicleID) VALUES (2, 4) 
INTO tblOptionDetail (OptionID, VehicleID) VALUES (1, 4) 
INTO tblOptionDetail (OptionID, VehicleID) VALUES (3, 4) 
INTO tblOptionDetail (OptionID, VehicleID) VALUES (6, 4) 
INTO tblOptionDetail (OptionID, VehicleID) VALUES (11, 4) 
INTO tblOptionDetail (OptionID, VehicleID) VALUES (12, 4) 
INTO tblOptionDetail (OptionID, VehicleID) VALUES (14, 4) 
INTO tblOptionDetail (OptionID, VehicleID) VALUES (15, 4) 
INTO tblOptionDetail (OptionID, VehicleID) VALUES (19, 4) 
INTO tblOptionDetail (OptionID, VehicleID) VALUES (4,5) 
INTO tblOptionDetail (OptionID, VehicleID) VALUES (8,5) 
INTO tblOptionDetail (OptionID, VehicleID) VALUES (1,5) 
INTO tblOptionDetail (OptionID, VehicleID) VALUES (2,5) 
INTO tblOptionDetail (OptionID, VehicleID) VALUES (5,5) 
INTO tblOptionDetail (OptionID, VehicleID) VALUES (21,6) 
INTO tblOptionDetail (OptionID, VehicleID) VALUES (22,6) 
INTO tblOptionDetail (OptionID, VehicleID) VALUES (3,6) 
INTO tblOptionDetail (OptionID, VehicleID) VALUES (1,6) 
INTO tblOptionDetail (OptionID, VehicleID) VALUES (2,6) 
INTO tblOptionDetail (OptionID, VehicleID) VALUES (1,7) 
INTO tblOptionDetail (OptionID, VehicleID) VALUES (4,7) 
INTO tblOptionDetail (OptionID, VehicleID) VALUES (5,7) 
INTO tblOptionDetail (OptionID, VehicleID) VALUES (2,7) 
SELECT * FROM dual; 

COMMIT; 

Answer 1

あなたは問題だこれがチェックされているもの。この文で

WHERE OPTIONDESC = 'GPS' AND OPTIONDESC = 
    (
    SELECT OPTIONDESC 
    FROM TBLOPTION 
    WHERE OPTIONDESC = 'Heated Seats' 
) 

されていますOPTIONDESCが2つの異なる値に等しいかどうか。単一の値は決してできない..それは似ているあなたはすべてのモデルには2つのオプションがありますしている取得しようとしている場合、あなたはDISTINCTオプションをCOUNTすることでGROUP BYを使用することができ、ここでORなくAND

を使用することができます

WHERE 1 = 1 and 1 = 2 

を尋ねます。

SELECT t1.MODELNAME AS Model, 
     t2.VEHICLEYEAR AS Year 
FROM TBLMODEL t1 
     JOIN TBLVEHICLE t2 ON t1.MODELID = t2.MODELID 
     JOIN TBLOPTIONDETAIL t3 ON t2.VEHICLEID = t3.VEHICLEID 
     JOIN TBLOPTION t4 ON t3.OPTIONID = t4.OPTIONID 
WHERE t4.OPTIONDESC IN ('GPS','Heated Seats') 
GROUP BY t1.MODELNAME, 
     t2.VEHICLEYEAR 
HAVING COUNT(DISTINCT t4.OPTIONDESC) = 2 

Answer 2

JamieD77からは既に回答があります。あなたはサブクエリを理解していないと言うので、私はちょうど、いくつかの工夫を追加したいとあなたのクエリは、この;-)

... AND OPTIONDESC = 
    (
    SELECT OPTIONDESC 
    FROM TBLOPTION 
    WHERE OPTIONDESC = 'Heated Seats' 
) 

サブクエリがここOPTIONDESCでTBLOPTIONからすべてのレコードを選択=「シートヒーターについて正しい示し'

このようなレコードが1つだけあるとします。次に、Heated Seatsという値を持つ行を1つ選択します。これは、OPTIONDESC（探していた値）であるHeated Seatsを選択したためです。結果は

... AND OPTIONDESC = 
    'Heated Seats' 

となります。または、OPTIONDESC = 'Heated Seats'のレコードはありません。次に、あなたは

... AND OPTIONDESC = 
    <nothing> 

となり、条件が満たされず、レコードを選択しないようにします。

OPTIONDESC = 'Heated Seats'のレコードが2つ以上あるとします。 DBMSは値を値の配列と比較できないため、クエリがクラッシュします。 OPTIONDESCに一意の制約がある場合、これは発生しません。そうしないと、むしろ

... AND OPTIONDESC IN (subquery) 

代わりの

... AND OPTIONDESC = (subquery) 

を使用します