我正在尝试使用XML文件和SqlBulkCopy插入数据。目标表是一个时间序列表，如下所示
create table TimeSeries (
Id uniqueidentifier constraint DF_TimeSeries_Id default (newid()) not null,
ObjectId uniqueidentifier not null,
[Date] datetime not null,
Value float(53) not null,
[Type] varchar (4) not null,
[Source] varchar (4) not null,
LastUpdate datetime constraint DF_TimeSeries_LastUpdate default (getdate()) not null,
TypeIndex smallint constraint DF_TimeSeries_TypeIndex default (0) not null,
constraint PK_TimeSeries primary key clustered ([Date] asc, ObjectId asc, [Type] asc, [Source] asc, TypeIndex asc) with (fillfactor = 80)
);
go
create nonclustered index [IX_TimeSeries_ObjectId_Type_Date_Source]
on TimeSeries(ObjectId asc, [Type] asc, [Date] asc, [Source] asc)
include(Value) with (fillfactor = 80);
go
create nonclustered index [IX_TimeSeries_ObjectId_Date]
on TimeSeries(ObjectId asc, [Date] asc)
include(Value) with (fillfactor = 80);
go
create table Beacons
(
BeaconId uniqueidentifier not null default newid(),
[Description] varchar(50) not null,
LocationX float not null,
LocationY float not null,
Altitude float not null
constraint PK_Beacons primary key clustered (BeaconId)
)
go
create index IX_Beacons on Beacons (BeaconId)
go
create table SnowGauges
(
SnowGaugeId uniqueidentifier not null default newid(),
[Description] varchar(50) not null
constraint PK_SnowGauges primary key clustered (SnowGaugeId)
)
go
create index IX_SnowGauges on SnowGauges (SnowGaugeId)
go
insert into Beacons ([Description], LocationX, LocationY, Altitude)
values ('Dunkery', 51.162, -3.586, 519), ('Prestwich', 53.527, -2.279, 76)
insert into SnowGauges ([Description]) values ('Val d''Isère')
select * from Beacons
select * from SnowGauges
如您所见，我想在TimeSeries中存储任何类型的时间序列。这可以是温度，压力，生物数据等......无论如何，我可以通过唯一标识符，来源和类型来识别时间序列。 ObjectId中没有设置外键，因为这个唯一标识符可以引用任何表。
在这个剧本的最后，我插入了2个信标和一个snowgauge，我想填写他们的时间序列。执行此操作的XML文件具有以下格式：
<?xml version="1.0" encoding="utf-8" ?>
<TimeSeries>
<TimeSeries ObjectId="186CA33E-AC1C-4220-81DE-C7CD32F40C1A" Date="09/06/2013 07:00:00" Value="9.2" Source = "Met Office" Type = "Temperature"/>
<TimeSeries ObjectId="186CA33E-AC1C-4220-81DE-C7CD32F40C1A" Date="09/06/2013 10:00:00" Value="8.8" Source = "Met Office" Type = "Temperature"/>
<TimeSeries ObjectId="186CA33E-AC1C-4220-81DE-C7CD32F40C1A" Date="09/06/2013 13:00:00" Value="8.7" Source = "Met Office" Type = "Temperature"/>
<TimeSeries ObjectId="186CA33E-AC1C-4220-81DE-C7CD32F40C1A" Date="09/06/2013 07:00:00" Value="1" Source = "Met Office" Type = "UV"/>
<TimeSeries ObjectId="186CA33E-AC1C-4220-81DE-C7CD32F40C1A" Date="09/06/2013 10:00:00" Value="3" Source = "Met Office" Type = "UV"/>
<TimeSeries ObjectId="186CA33E-AC1C-4220-81DE-C7CD32F40C1A" Date="09/06/2013 13:00:00" Value="5" Source = "Met Office" Type = "UV"/>
<TimeSeries ObjectId="AFB81E51-18B0-4696-9C2F-E6E9EEC1B647" Date="09/06/2013 07:00:00" Value="5.8" Source = "Met Office" Type = "Temperature"/>
<TimeSeries ObjectId="AFB81E51-18B0-4696-9C2F-E6E9EEC1B647" Date="09/06/2013 10:00:00" Value="6.3" Source = "Met Office" Type = "Temperature"/>
<TimeSeries ObjectId="AFB81E51-18B0-4696-9C2F-E6E9EEC1B647" Date="09/06/2013 13:00:00" Value="6.5" Source = "Met Office" Type = "Temperature"/>
<TimeSeries ObjectId="50E52A2B-D719-4341-A451-110D0874D26D" Date="07/06/2013 00:00:00" Value="80.5" Source = "Meteo France" Type = "SnowMeter"/>
<TimeSeries ObjectId="50E52A2B-D719-4341-A451-110D0874D26D" Date="08/06/2013 00:00:00" Value="80.5" Source = "Meteo France" Type = "SnowMeter"/>
</TimeSeries>
如果您运行第一个脚本，您可能会遇到不同的ObjectId，并且必须在XML文件中更新它们。所以从那里，一切都应该是直截了当的，一个简单的C＃程序应该完成插入数据的工作。我们现在来看看C＃代码：
using System;
using System.Data;
using System.Data.SqlClient;
using System.IO;
namespace XMLBulkInsert
{
class Program
{
const string XMLFILE_PATH = @"C:\Workspaces\Ws1\R\TimeSeries\TimeSeries.xml";
const string CONNECTION_STRING = @"Server=RISK1;Database=DevStat;Trusted_Connection=True;";
static void Main(string[] args)
{
StreamReader xmlFile = new StreamReader(XMLFILE_PATH);
DataSet ds = new DataSet();
Console.Write("Read file... ");
ds.ReadXml(xmlFile);
DataTable sourceData = ds.Tables[0];
Console.WriteLine("Done !");
using (SqlConnection sourceConnection = new SqlConnection(CONNECTION_STRING))
{
sourceConnection.Open();
using (SqlBulkCopy bulkCopy = new SqlBulkCopy(sourceConnection.ConnectionString))
{
bulkCopy.ColumnMappings.Add("ObjectId", "ObjectId");
bulkCopy.ColumnMappings.Add("Date", "Date");
bulkCopy.ColumnMappings.Add("Value", "Value");
bulkCopy.ColumnMappings.Add("Source", "Source");
bulkCopy.ColumnMappings.Add("Type", "Type");
bulkCopy.DestinationTableName = "TimeSeries";
try
{
Console.Write("Insert data... ");
bulkCopy.WriteToServer(sourceData);
}
catch (Exception ex)
{
Console.WriteLine(ex.Message);
}
finally
{
xmlFile.Close();
sourceConnection.Close();
}
}
}
Console.WriteLine("Insertion completed, please Press Enter...");
Console.ReadLine();
}
}
}
运行此程序将返回此异常：“数据源中String类型的给定值无法转换为指定目标列的uniqueidentifier类型。”看起来我没有办法设置映射来强制列成为uniqueidentifier。我甚至尝试插入此代码ds.Tables[0].Columns[0].DataType = typeof(Guid);但没有成功，一旦表有行数据，.Net就无法更改列的类型。
我对SQlBulkCopy有很高的例外，但现在我觉得有点卡住了。我有数百万个XML格式的数据，由于这个uniqueidentifier，无法插入任何数据。
是否有人知道如何设置此类以接受唯一标识符？
答案 0 :(得分：2)
鉴于有关3亿行的评论，我会忘记关于DataTable;您不希望一次加载所有数据。理想的是逐个元素地解析它，将数据公开为IDataReader。
幸运的是，存在一些实用程序。首先，让我们解析数据。每一行基本上都是：
class TimeSeries
{
public Guid ObjectId { get; set; }
public DateTime Date { get; set; }
public string Source { get; set; }
public string Type { get; set; }
public decimal Value { get; set; }
}
我们可以写一个基于元素的阅读器，如：
static IEnumerable<TimeSeries> ReadTimeSeries(TextReader source)
{
using (var reader = XmlReader.Create(source, new XmlReaderSettings {
IgnoreWhitespace = true }))
{
reader.MoveToContent();
reader.ReadStartElement("TimeSeries");
while(reader.Read() && reader.NodeType == XmlNodeType.Element
&& reader.Depth == 1)
{
using (var subtree = reader.ReadSubtree())
{
var el = XElement.Load(subtree);
var obj = new TimeSeries
{
ObjectId = (Guid) el.Attribute("ObjectId"),
// note: datetime is not xml format; need to parse - this
// should probably be more explicit
Date = DateTime.Parse((string) el.Attribute("Date")),
Source = (string) el.Attribute("Source"),
Type = (string)el.Attribute("Type"),
Value = (decimal)el.Attribute("Value")
};
yield return obj;
}
}
}
}
请注意，这是一个“迭代器块”，并且是懒惰的假脱机 - 它不会立即加载所有数据。
接下来，我们需要一个可以使用IEnumerable<T>的API，并将其公开为IDataReader - FastMember完成此操作（以及许多其他事情）。所以我们可以写一下：
using(var bcp = new SqlBulkCopy(connection))
using(var objectReader = ObjectReader.Create(ReadTimeSeries(source)))
{
bcp.DestinationTableName = "SomeTable";
bcp.WriteToServer(objectReader);
}
其中source是TextReader，例如来自File.OpenText：
using(var source = File.OpenText(path))
using(var bcp = new SqlBulkCopy(connection))
using(var objectReader = ObjectReader.Create(ReadTimeSeries(source)))
{
bcp.DestinationTableName = "SomeTable";
bcp.WriteToServer(objectReader);
}
如果您想控制列顺序，可以使用bcp.ColumnMappings - 但也许更方便的是让IDataReader在内部执行此操作：
using(var objectReader = ObjectReader.Create(
ReadTimeSeries(source, "ObjectId", "Date", "Value" /* etc */)))
{
bcp.DestinationTableName = "SomeTable";
bcp.WriteToServer(objectReader);
}
我将这个用于我自己的一些代码 - 即使数据 适合内存，它比通过DataTable 更快。< / p>
关键的一点是，我们现在可以控制正在发生的事情。