如何插入標識值到另一個表

Question

我有兩個表：

create table Clients 
(
    id_client int not null identity(1,1) Primary Key, 
    name_client varchar(10) not null, 
    phone_client int not null 
) 

create table Sales 
(
    id_sale int not null identity(1,1) Primary Key, 
    date_sale date not null, 
    total_sale float not null 
    id_clients int not null identity(1,1) Foreign Key references Clients 
) 

所以，讓我們插入到客戶端（「拉爾夫」，00000000），該id_client將是1（明顯）。問題是：我如何將1插入銷售？

Answer 1

首先 - 你不能有兩列在任何表定義爲identity - 你會得到

消息2744，級別16，狀態2，行指定1個
多重身份列的錯誤表'銷售'。每個表只允許有一個標識列。

因此，您將無法實際創建Sales表。

在Sales表引用一個identity列中的id_clients列 - 但其本身，它應該不被定義爲身份 - 它得到任何價值你的客戶了。

create table Sales 
(
    id_sale int not null identity(1,1) Primary Key, 
    date_sale date not null, 
    total_sale float not null 
    id_clients int not null foreign key references clients(id_client) 
) 

-- insert a new client - this will create an "id_client" for that entry 
insert into dbo.Clients(name_client, phone_client) 
values('John Doe', '+44 44 444 4444') 

-- get that newly created "id_client" from the INSERT operation 
declare @clientID INT = SCOPE_IDENTITY() 

-- insert the new "id_client" into your sales table along with other values 
insert into dbo.Sales(......, id_clients) 
values(......., @clientID)