对象不能从DBNull转换为其他类型。
我有一个函数,会抛出上述错误。在存储过程和C#代码中,我处理了所有的null值。
那么它是在哪里得到这个错误的呢?
我可以在catch块中看到错误。但我不明白在以下create()函数的哪一行引发了该错误。
public Boolean Create(DataTO DataTO)
{
IDbTrans transaction = null;
IDbCmd IDbCmd;
string EncryptedPassword = Encrypt(DataTO.txtPwd);
Base dataAccCom = null;
try
{
dataAccCom = Factory.Create();
dataAccCom.OpenConnection();
transaction = dataAccCom.BeginTransaction();
IDbCmd = dataAccCom.CreateCommand("sp_Register", true);
dataAccCom.AddParameter(IDbCmd, "op_Id", DbType.Int64, 0, ParameterDirection.Output);
dataAccCom.AddParameter(IDbCmd, "p_dlstTitle", DbType.String, ReplaceNull(DataTO.dlstTitle));
dataAccCom.AddParameter(IDbCmd, "p_txtFirstName", DbType.String, ReplaceNull(DataTO.txtFirstName));
dataAccCom.AddParameter(IDbCmd, "p_txtMiddleName", DbType.String, ReplaceNull(DataTO.txtMiddleName));
dataAccCom.AddParameter(IDbCmd, "p_txtLastName", DbType.String, ReplaceNull(DataTO.txtLastName));
dataAccCom.AddParameter(IDbCmd, "p_txtDob", DbType.DateTime, DataTO.txtDob);
dataAccCom.AddParameter(IDbCmd, "p_txtDesig", DbType.String, ReplaceNull(DataTO.txtDesig));
dataAccCom.AddParameter(IDbCmd, "p_txtOFlatNo", DbType.String, ReplaceNull(DataTO.txtOFlatNo));
dataAccCom.AddParameter(IDbCmd, "p_txtOBuild", DbType.String, ReplaceNull(DataTO.txtOBuild));
dataAccCom.AddParameter(IDbCmd, "p_txtOPost", DbType.String, ReplaceNull(DataTO.txtOPost));
dataAccCom.AddParameter(IDbCmd, "p_txtOArea", DbType.String, ReplaceNull(DataTO.txtOArea));
dataAccCom.AddParameter(IDbCmd, "p_txtOCity", DbType.String, ReplaceNull(DataTO.txtOCity));
dataAccCom.AddParameter(IDbCmd, "p_txtRBuild", DbType.String, ReplaceNull(DataTO.txtRBuild));
dataAccCom.AddParameter(IDbCmd, "p_txtRPost", DbType.String, ReplaceNull(DataTO.txtRPost));
dataAccCom.AddParameter(IDbCmd, "p_txtUserID", DbType.String,ReplaceNull(DataTO.txtUserID));
dataAccCom.AddParameter(IDbCmd, "p_txtPwd", DbType.String, ReplaceNull(EncryptedPassword));
dataAccCom.ExecuteNonQuery(IDbCmd);
DataTO.Id = Convert.ToInt64(dataAccCom.GetParameterValue(IDbCmd, "op_Id"));
transaction.Commit();
return true;
}
catch (System.Exception ex)
{
if (transaction != null)
{
transaction.Rollback();
}
throw ex;
}
finally
{
transaction = null;
if (dataAccCom != null)
{
dataAccCom.CloseConnection();
}
dataAccCom = null;
IDbCmd = null;
}
}
public string ReplaceNull(string value)
{
if (value == null)
{
return "";
}
else
{
return value;
}
}
public DateTime ReplaceNull(DateTime value)
{
if (value == null)
{
return DateTime.Now;
}
else
{
return value;
}
}
public double ReplaceNull(double value)
{
if (value == null)
{
return 0.0;
}
else
{
return value;
}
}
double
和DateTime
上的ReplaceNull
重载是无用的。这些类型的值永远不可能为 null,因此永远不会通过if (value == null)
条件。 - Anthony Pegram