请注意，如果您用;结束每一行，SET IDENTITY_INSERT mytable ON命令将不适用于以下行。

即。 像这样的查询

SET IDENTITY_INSERT mytable ON;
INSERT INTO mytable (VoucherID, name) VALUES (1, 'Cole');

给出错误 当IDENTITY_INSERT设置为OFF时，无法为表'mytable'中的身份列插入显式值。

但是像这样的查询是可以的:

SET IDENTITY_INSERT mytable ON
INSERT INTO mytable (VoucherID, name) VALUES (1, 'Cole')
SET IDENTITY_INSERT mytable OFF;

SET IDENTITY_INSERT命令似乎只适用于事务，而;将表示事务的结束。

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)]

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 

使用实体框架与这样的模型有同样的问题(我简化了原始代码):

public class Pipeline
{
  public Pipeline()
  {
     Runs = new HashSet<Run>();
  }

  public int Id {get; set;}
  public ICollection<Run> Runs {get;set;}
}

public class Run
{
  public int Id {get; set;}
  public int RequestId {get; set;}
  public Pipeline Pipeline {get;set;}
}

运行与管道有多对1的关系(一个管道可以运行多次)

在我的RunService中，我注入了dbcontext作为上下文。DbContext有一个Runs DbSet。我在RunService中实现了这个方法:

public async Task<Run> CreateAndInit(int requestId, int pplId)
{
  Pipeline pipeline = await pipelineService.Get(pplId).FirstOrDefaultAsync().ConfigureAwait(false);
  Run newRun = new Run {RequestId = requestId, Pipeline = pipeline};
  context.Runs.Add(newRun);
  await context.SaveChangesAsync().ConfigureAwait(false); // got exception in this line
  return newRun;
}

当方法执行时，我得到了这个异常:

Exception has occurred: CLR/Microsoft.EntityFrameworkCore.DbUpdateException
Exception thrown: 'Microsoft.EntityFrameworkCore.DbUpdateException' in System.Private.CoreLib.dll: 'An error occurred while updating the entries. See the inner exception for details.'
 Inner exceptions found, see $exception in variables window for more details.
 Innermost exception     Microsoft.Data.SqlClient.SqlException : Cannot insert explicit value for identity column in table 'Pipelines' when IDENTITY_INSERT is set to OFF.

对我来说，解决方案是将对象和关系的创建分开

public async Task<Run> CreateAndInit(int requestId, int pplId)
{
  Pipeline pipeline = await pipelineService.Get(pplId).FirstOrDefaultAsync().ConfigureAwait(false);
  Run newRun = new Run {RequestId = requestId};
  context.Runs.Add(newRun);
  newRun.Pipeline = pipeline; // set the relation separately
  await context.SaveChangesAsync().ConfigureAwait(false); // no exception
  return newRun;
}

如果您正在使用liquibase更新SQL Server，则可能试图将记录键插入到autoIncrement字段中。通过从插入中删除列，脚本应该可以运行。

<changeSet id="CREATE_GROUP_TABLE" >
    <createTable tableName="GROUP_D">
        <column name="GROUP_ID" type="INTEGER" autoIncrement="true">
            <constraints primaryKey="true"/>
        </column>
    </createTable>
</changeSet>

<changeSet id="INSERT_UNKNOWN_GROUP" >
    <insert tableName="GROUP_D">    

        <column name="GROUP_ID" valueNumeric="-1"/>
 ...
    </insert>
</changeSet>

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。