最好的解决方案是使用GeneratedValue(strategy =…)注释，即。

@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
@Column ...
private int OperationID;

它说，这个列是由数据库使用IDENTITY策略生成的，你不需要关心-数据库会做的。

This occurs when you have a (Primary key) column that is not set to Is Identity to true in SQL and you don't pass explicit value thereof during insert. It will take the first row, then you wont be able to insert the second row, the error will pop up. This can be corrected by adding this line of code [DatabaseGenerated(DatabaseGeneratedOption.Identity)] in your PrimaryKey column and make sure its set to a data type int. If the column is the primary key and is set to IsIDentity to true in SQL there is no need for this line of code [DatabaseGenerated(DatabaseGeneratedOption.Identity)] this also occurs when u have a column that is not the primary key, in SQL that is set to Is Identity to true, and in your EF you did not add this line of code [DatabaseGenerated(DatabaseGeneratedOption.Identity)]

在该表的实体中，将DatabaseGenerated属性添加到标识插入设置的列之上:

例子:

[DatabaseGenerated(DatabaseGeneratedOption.Identity)]
public int TaskId { get; set; }

最好的解决方案是使用GeneratedValue(strategy =…)注释，即。

@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
@Column ...
private int OperationID;

它说，这个列是由数据库使用IDENTITY策略生成的，你不需要关心-数据库会做的。

我通过每次向数据库添加任何东西时创建一个新对象来解决这个问题。

您正在为OperationId插入值，这是一个标识列。

您可以像这样在表上打开标识插入，以便您可以指定自己的标识值。

SET IDENTITY_INSERT Table1 ON

INSERT INTO Table1
/*Note the column list is REQUIRED here, not optional*/
            (OperationID,
             OpDescription,
             FilterID)
VALUES      (20,
             'Hierachy Update',
             1)

SET IDENTITY_INSERT Table1 OFF