Question

CREATE TABLE Masina(    
    idMasina INT PRIMARY KEY NOT NULL,    
    marca VARCHAR(20),     
    model VARCHAR(20),    
    pretFaraDotari DOUBLE
);

CREATE TABLE Dotari(    
    idDotare INT PRIMARY KEY NOT NULL,    
    dotare VARCHAR(30),    
    pret INT
);

CREATE TABLE Comenzi(    
    idComanda INT PRIMARY KEY NOT NULL,    
    idMasina INT,    
    pretTotal DOUBLE,    
    discount VARCHAR(10),    
    FOREIGN KEY (idMasina)
    REFERENCES Masina(idMasina) ON DELETE CASCADE ON UPDATE CASCADE
);

CREATE TABLE Com_Dot(
    idComanda INT,
    idDotare INT,
    FOREIGN KEY (idComanda)
    REFERENCES Comenzi(idComanda) ON DELETE CASCADE ON UPDATE CASCADE,

    FOREIGN KEY (idDotare)
    REFERENCES Dotari(idDotare) ON DELETE CASCADE ON UPDATE CASCADE
);

我如何展示＆＃34; marca＆＃34;，＆＃34; model＆＃34;，＆＃34; pretFaraDotari＆＃34;来自＆＃34; Masina＆＃34;表，＆＃34; dotare＆＃34;的总价来自＆＃34; Dotari＆＃34; table，＆＃34; pretFaraDotari＆＃34; + dotare的总价格，＆＃34; pretTotal＆＃34;来自＆＃34; Comenzi＆＃34;表中所有条目的表格＆＃34; Comenzi＆＃34;？

我需要使用一个命令显示所有这些......这是一个大问题

Answer 1

我不知道我是否“完全”得到它（我不会说罗马尼亚语）但也许你正在寻找像

这样的东西

select 
    cd.*,  
    c.*,
    d.*,
    m.*
from Com_Dot as cd,
join Comenzi as c on c.idComanda = cd.idComanda
join Dotari as d on d.idDotare = cd.idDotare
join Masina as m on m.idMasina = c.idMasina

如果您需要某种聚合，可以根据需要添加where / group。

INNER JOIN在这里有用吗？

1 个答案: