Question

我尝试过不同的方法来实现子查询

但最终尝试使用合作。收效甚微

主要任务是找出在ACIER中指定一个或多个PRODUITS的COMMANDES（NCOM）有多少（如此计数）

 select count(NCOM) as COUNT
 from   Detail D, Produit P
 where  D.NPRO = P.NPRO
 and    P.LIBELLE = '%ACIER%'

它总是给我一个0计数

我不知道子查询是否会更容易，但我现在无法到达任何地方。

下面你可以查看我的表格创建和插入

create table CLIENT
(NCLI char(4) not null,
 NOM  varchar(12) not null,
 ADRESSE varchar(20) not null,
 LOCALITE varchar(12) not null,
 CAT char(2),
 COMPTE decimal(9,2) not null,
 primary key (NCLI));

create table PRODUIT
(NPRO char(5) not null,
 LIBELLE varchar(20) not null,
 PRIX decimal(5,0) not null,
 QSTOCK decimal(6,0) not null,
 primary key (NPRO));

create table COMMANDE
(NCOM char(5) not null,
 NCLI char(4) not null,
 DATECOM datetime not null,
 primary key (NCOM),
 foreign key (NCLI) references CLIENT);

create table DETAIL
(NCOM char(5) not null,
 NPRO char(5) not null,
 QCOM decimal(4,0) not null,
 primary key (NCOM,NPRO),
 foreign key (NCOM) references COMMANDE,
 foreign key (NPRO) references PRODUIT);



insert into CLIENT values ('B112','HANSENNE'    ,'23, a. Dumont'       ,'Poitiers' ,'C1',1250.00);
insert into CLIENT values ('C123','MERCIER'     ,'25, r. Lemaitre'     ,'Namur'    ,'C1',-2300);
insert into CLIENT values ('B332','MONTI'       ,'112, r. Neuve'       ,'Geneve'   ,'B2',0);
insert into CLIENT values ('F010','TOUSSAINT'   ,'5, r. Godefroid'     ,'Poitiers' ,'C1',0);
insert into CLIENT values ('K111','VANBIST'     ,'180, r. Florimont'   ,'Lille'    ,'B1',720);
insert into CLIENT values ('S127','VANDERKA'    ,'3, av. des Roses'    ,'Namur'    ,'C1',-4580);
insert into CLIENT values ('B512','GILLET'      ,'14, r. de l''Ete'    ,'Toulouse' ,'B1',-8700);
insert into CLIENT values ('B062','GOFFIN'      ,'72, r. de la Gare'   ,'Namur'    ,'B2',-3200);
insert into CLIENT values ('C400','FERARD'      ,'65, r. du Tertre'    ,'Poitiers' ,'B2',350);
insert into CLIENT values ('C003','AVRON'       ,'8, ch. de la Cure'   ,'Toulouse' ,'B1',-1700);
insert into CLIENT values ('K729','NEUMAN'      ,'40, r. Bransart'     ,'Toulouse' ,NULL,0);
insert into CLIENT values ('F011','PONCELET'    ,'17, Clos des Erables','Toulouse' ,'B2',0);
insert into CLIENT values ('L422','FRANCK'      ,'60, r. de Wepion'    ,'Namur'    ,'C1',0);
insert into CLIENT values ('S712','GUILLAUME'   ,'14a, ch. des Roses'  ,'Paris'    ,'B1',0);
insert into CLIENT values ('D063','MERCIER'       ,'201, bvd du Nord'  ,'Toulouse' ,NULL,-2250);
insert into CLIENT values ('F400','JACOB'       ,'78, ch. du Moulin'   ,'Bruxelles','C2',0);

insert into PRODUIT values ('CS262','CHEV. SAPIN 200x6x2',  75,  45);
insert into PRODUIT values ('CS264','CHEV. SAPIN 200x6x4', 120,2690);
insert into PRODUIT values ('CS464','CHEV. SAPIN 400x6x4', 220, 450);
insert into PRODUIT values ('PA45' ,'POINTE ACIER 45 (1K)',105, 580);
insert into PRODUIT values ('PA60' ,'POINTE ACIER 60 (1K)', 95, 134);
insert into PRODUIT values ('PH222','PL. HETRE 200x20x2',  230, 782);
insert into PRODUIT values ('PS222','PL. SAPIN 200x20x2',  185,1220);

insert into COMMANDE values ('30178','K111','20081221');
insert into COMMANDE values ('30179','C400','20081222');
insert into COMMANDE values ('30182','S127','20081223');
insert into COMMANDE values ('30184','C400','20081223');
insert into COMMANDE values ('30185','F011','20090102');
insert into COMMANDE values ('30186','C400','20090102');
insert into COMMANDE values ('30188','B512','20090103');

insert into DETAIL values ('30178','CS464',25);
insert into DETAIL values ('30179','PA60',20);
insert into DETAIL values ('30179','CS262',60);
insert into DETAIL values ('30182','PA60',30);
insert into DETAIL values ('30184','CS464',120);
insert into DETAIL values ('30184','PA45',20);
insert into DETAIL values ('30185','PA60',15);
insert into DETAIL values ('30185','PS222',600);
insert into DETAIL values ('30185','CS464',260);
insert into DETAIL values ('30186','PA45',3);
insert into DETAIL values ('30188','PA60',70);
insert into DETAIL values ('30188','PH222',92);
insert into DETAIL values ('30188','CS464',180);
insert into DETAIL values ('30188','PA45',22);

Answer 1

在你的where子句中=。你必须使用LIKE ...... LIKE'％ACIER％'

 select count(NCOM) as COUNT
 from   DETAIL D
 JOIN PRODUIT P ON D.NPRO = P.NPRO
 where P.LIBELLE LIKE '%ACIER%'

Answer 2

请使用LIKE而不是=。喜欢这个

    select count(NCOM) as COUNT
 from   Detail D, Produit P
 where  D.NPRO = P.NPRO
 and    P.LIBELLE LIKE '%ACIER%'

尝试使用子查询和关节进行计数查询

2 个答案: