Question

下面是一段包含两部分的代码。几乎彼此相同。它们都将一些东西插入表中，然后调用Scope_identity。我已经检查确保插入了AddressType，它给了我CityId就好了。我看不出差异。我查看了代码，找不到我的错误。我希望有人可以成为额外的一双眼睛，并指出我确信，这肯定是一个明显的错误。

SqlCommand addressTypeCommand = new SqlCommand(
       "INSERT INTO AddressType VALUES ('" + customerRow.AddressType + "');",
                    newCustConnection);
try
{
    addressTypeCommand.ExecuteNonQuery();
}
catch (SqlException addressTypeException)
{
    if (addressTypeException.ToString().StartsWith(
             "Violation of UNIQUE KEY constraint"))
    {
        Console.WriteLine("Unique Key exception on 'AddressType'.");
    }
}

SqlCommand selectAddressTypeID = new SqlCommand(
      "select SCOPE_IDENTITY();", newCustConnection);
string addressTypeID = selectAddressTypeID.ExecuteScalar().ToString();

SqlCommand cityCommand = new SqlCommand(
       "INSERT INTO City VALUES ('" + customerRow.City + "');", 
       newCustConnection);
try
{
    cityCommand.ExecuteNonQuery();
}
catch (SqlException cityException)
{
    if (cityException.ToString().StartsWith(
             "Violation of UNIQUE KEY constraint"))
    {
        Console.WriteLine("Unique Key exception on 'City'.");
    }
}
SqlCommand selectCityID = new SqlCommand(
       "select SCOPE_IDENTITY();", newCustConnection);
string cityID = selectCityID.ExecuteScalar().ToString();

Answer 1

要使用scope_identity()，您需要与插入位于同一范围内。实现此目的的最简单方法是将其作为同一批次的一部分传递。

e.g。

SqlCommand addressTypeCommand = new SqlCommand(
   "insert into AddressType values (@addressType); select scope_identity()"
);

addressTypeCommand.Parameters.AddWithValue(
    // replace with correct datatype, possibly set data length
    "@addressType", SqlDbType.VarChar, customerRow.AddressType
);
addressTypeID = addressTypeCommand.ExecuteScalar().ToString();

Scope_Identity（）返回一个空字符串

1 个答案: