尝试在sql中创建外键时继续出错？

CREATE TABLE Room ( RoomID nvarchar(8) PRIMARY KEY, Capacity numeric(3)

CREATE TABLE Room(RoomID nvarchar(8)PRIMARY KEY,容量数字(3)

)

CREATE TABLE RoomType ( RoomType nvarchar(2) primary key, Description nvarchar(20), Responsiblity nvarchar(20) )

CREATE TABLE RoomType(RoomType nvarchar(2)主键,描述nvarchar(20),Responsiblity nvarchar(20))

alter table Room

改变房间

add constraint fk_type foreign key (Type) references RoomType(Type)

添加约束fk_type外键(Type)引用RoomType(Type)

Major Error 0x80040E11, Minor Error 0

重大错误0x80040E11,轻微错误0

alter table Room add constraint fk_type foreign key (Type) references RoomType(Type) Invalid column ID. [ Type ]

alter table房间添加约束fk_type外键(类型)引用RoomType(Type)无效的列ID。 [类型]

1 个解决方案

#1

You can create a table RoomEquipment that combines RoomID and EquipmentType like this:

您可以创建一个RoomEquipment表,它将RoomID和EquipmentType组合在一起,如下所示:

create table RoomEquipment (
  RoomID int,
  EquipmentType nvarchar(1),
  primary key (roomid, equipmenttype),
  constraint fk_roomequipment_equipment_type 
             foreign key (equipmenttype) 
             references equipment(equipmenttype),
  constraint fk_roomequipment_equipment_roomid
             foreign key (roomid) 
             references room(roomid)
);

Other tables may look like this:

其他表可能如下所示:

-- I prefer using char datatype for predictable number of characters in a field
CREATE TABLE RoomType (
Roomtype nvarchar(2) NOT NULL,
Description nvarchar(20),
Responsibility nvarchar(20),
primary key (Roomtype)
);

-- You could use char(1) instead of nvarchar(1) for type; I'd prefer using int instead
create table Equipment (
Equipmenttype nvarchar(1) NOT NULL,
Description nvarchar(10)
);

-- Added a unique key to assist with good foreign key relationship
alter table Equipment add constraint uk_equipment_equipmenttype unique (equipmenttype);

-- Just use an int or char if roomID length is predictable
Create table Room (
RoomID nvarchar(8),
Capacity numeric(3),
Roomtype(fk,nvarchar(2)
);

alter table room add constraint uk_room_id unique (roomid);

Example is here: http://sqlfiddle.com/#!3/f510b

示例如下:http://sqlfiddle.com/#!3 / f510b

#1