无法创建多个ID，但我只有一个

Question

如您所见，我正在用一个主键创建一个新类，我删除了数据库以重新创建它，但是public class CustomerContracts{    [Key, Column("ItemId")]  //This change the name of the column when you are using migration.  If you have a form created already, you have to change the connection in the for to aim the new column name.      public int ItemId { get; set; }    public string Description { get; set; }    public string CustomerRef { get; set; }    public int ContractTypeId { get; set; }    public DateTime StartDate { get; set; }    public DateTime EndDate { get; set; }    public bool isActive { get; set; }    [DecimalPrecision(18, 2)]    public decimal Price { get; set; }}但是，当我尝试更新数据库时，出现以下错误。指定“ -Verbose”标志以查看应用于目标数据库的SQL语句。应用显式迁移：[201804260855058_firstmigration]。应用显式迁移：201804260855058_firstmigration。System.Data.SqlClient.SqlException（0x80131904）：为表'CustomerContracts'指定了多个标识列。每个表只允许一个标识列。在System.Data.SqlClient.SqlConnection.OnError（SqlException异常，布尔值breakConnection，操作1 wrapCloseInAction)     at System.Data.SqlClient.SqlInternalConnection.OnError(SqlException exception, Boolean breakConnection, ActionSystem.Data.SqlClient.TdsParser.TryRun（RunBehavior runBehavior，SqlCommand cmdHandler，SqlDataReadS数据状态，BulkStateCopySimpleState，ObjectDataCopyS，ObjectState，ObjectState，ObjectState，ObjectState，ObjectState，ObjectState，ObjectState，ObjectState，ObjectState，ObjectState，ObjectState，ObjectState，ObjectState，ObjectState，ObjectState，ObjectState，ObjectState，ObjectState，ObjectState，ObjectState，ObjectState，ObjectState，ObjectState，ObjectState，ObjectState，ObjectState，对象状态，对象状态，对象类型dataReady）位于System.Data.SqlClient.SqlCommand.RunExecuteNonQueryTds（字符串methodName，布尔异步，Int32超时，布尔asyncWrite）位于System.Data.SqlClient.SqlCommand.InternalExecuteNonQuery（TaskCompletionSource 1 completion, String methodName, Boolean sendToPipe, Int32 timeout, Boolean& usedCache, Boolean asyncWrite, Boolean inRetry)     at System.Data.SqlClient.SqlCommand.ExecuteNonQuery()     at 

Answer 1

试试这个：

public override void Up()

{

    DropPrimaryKey("dbo.CustomerContracts");

    DropColumn("dbo.CustomerContracts", "TeamId"); // Drop this first

    AddColumn("dbo.CustomerContracts", "ItemId", c => c.Int(nullable: false, identity: true));

    AddPrimaryKey("dbo.CustomerContracts", "ItemId");

}