android studio 找不到reosurce,EF 6 Bridge Table Insert Not Working

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最新推荐文章于 2025-02-21 10:53:45 发布

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文章标签： android studio 找不到reosurce

在尝试使用Entity Framework (EF) 创建一个新的订单并关联资源时，遇到SQL错误，提示违反主键约束，无法插入重复键值。问题出现在尝试将ID为2的资源类型添加到订单中，而该键值已经存在。代码示例展示了如何添加资源类型到订单，以及订单、资源类型和桥接表的数据库结构。博主期望桥接表在添加订单（ID=1）和两个资源（car ID=1和van ID=2）后能正确显示。

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问题

I am still trying to learn how to use EF and running into a problem with my bridge table.

When I try to create a new Order with associated Resources, I get the following SQL error:

{"Violation of PRIMARY KEY constraint 'PK_Resource_Type'. Cannot insert duplicate key in object 'dbo.Resource_Type'. The duplicate key value is (2).\r\nThe statement has been terminated."}

Code Looks like this

ResourceType resource = new ResourceType();

resource.ID = 2;

resource.Name = "Van"

order.resourceType().Add(resource)

db.Orders.Add(order);

db.SaveChanges();

Tables look like this

--Order table

CREATE TABLE [dbo].[Orders](

[Order_ID] [int] IDENTITY(1,1) NOT NULL,

[OrdernName] [varchar](100) NOT NULL,

CONSTRAINT [PK_Orders] PRIMARY KEY CLUSTERED

(

[Order_ID] ASC

)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]

) ON [PRIMARY]

--Resource Type table

CREATE TABLE [dbo].[Resource_Type](

[ResourceType_ID] [int] NOT NULL,

[ResourceType] [varchar] (30) NOT NULL

CONSTRAINT [PK_Resource_Type] PRIMARY KEY CLUSTERED

(

[ResourceType_ID] ASC

)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]

) ON [PRIMARY]

--Resource Type To Order table

CREATE TABLE [dbo].[Resource_Type_Order](

[ResourceType_ID] [int] NOT NULL,

[Order_ID] [int] NOT NULL

CONSTRAINT [PK_Resource_Type_Order] PRIMARY KEY CLUSTERED

(

[ResourceType_ID] ASC,

[Order_ID] ASC

)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]

) ON [PRIMARY]

ALTER TABLE [dbo].[Resource_Type_Order] WITH CHECK ADD CONSTRAINT FK_Order_Resource_Type_Order FOREIGN KEY([Order_ID])

REFERENCES [dbo].[Orders]([Order_ID])

ALTER TABLE [dbo].[Resource_Type_Order] WITH CHECK ADD CONSTRAINT FK_Resource_Type_Order_Resource_Type FOREIGN KEY([ReosurceType_ID])

REFERENCES [dbo].[Resource_Type]([Resource_ID])

Am I using the bridge table correctly? I want my bridge table to look like this, after I add an order (ID=1) with two resources (car ID=1 and van ID=2).