SQL 如何在查询中要求一个值乘以倍数

Question

大家晚上好！

以下问题，我有三个表：

Create TABLE Suppliers (
SID integer,
sname varchar(50),
adress varchar(50),
PRIMARY KEY (SID)
)

Create TABLE Parts (
PID integer,
pname varchar(50),
color varchar(50),
PRIMARY KEY (PID)
)

Create TABLE Catalog (
SID integer,
PID Integer,
costreal integer,
PRIMARY KEY (PID,SID)
)

我要回答的问题是：

"Find the ids of suppliers who supply some red part and some green part."

希望你能帮帮我！

Answer 1

这听起来像是 having 的聚合和过滤：

select s.sid
from suppliers s
inner join catalog c on c.sid = s.sid
inner join parts p on p.pid = c.pid
where p.color in ('red', 'green')    -- either one or the other
group by s.id
having min(p.color) <> max(p.color)  -- both are present

SQL 如何在查询中要求一个值乘以倍数

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