SQLServer2005中利用xml类型实现批量操作的存储过程[原]

实现批量操作是常见的任务，比如批量删除一批数据，如果在应用程序端循环调用DAL.Entity.Delete则效率非常低，因为数据库往返次数取决与数据量大小。而编写一个存储过程效率更高。

做这个批量操作的存储过程使用什么作为参数是一个问题。如果使用VARCHAR(MAX)，内容是，例如要删除记录的id并以逗号隔开，例如“1,2,3,4,…..”，这样的话就会存在最大长度受限制的问题。

这儿介绍一种使用XML的VARBINARY类型作为参数的高效方法。

首先是xml的格式：

<Employees>

<Employee EmployeeID="1" EmployeeName="Bush" EmployeeAddress="WashtonD.C." />

<Employee EmployeeID="2" EmployeeName="Jamson" EmployeeAddress="Russia" />

<Employee EmployeeID="3" EmployeeName="Brown" EmployeeAddress="London" />

</Employees>

 

把这个XML转换为Binary类型：

 

using System.IO;

using System.Xml;

private byte[] GetEmployeesListXmlStream(IList EmployeesList)

{

byte[] result = null;

using (MemoryStream stream = new MemoryStream())

{

XmlWriterSettings settings = new XmlWriterSettings();

settings.Indent = true;

settings.OmitXmlDeclaration = true;

settings.IndentChars = "\t";

XmlWriter writer = XmlWriter.Create(stream, settings);

writer.WriteStartDocument();

writer.WriteStartElement("Employees");

foreach (Employee var in EmployeesList)

{

writer.WriteStartElement("Employee");

writer.WriteAttributeString("EmployeeID", var.EmployeeID.ToString());

writer.WriteAttributeString("EmployeeName", var.EmployeeName);

writer.WriteAttributeString("EmployeeAddress", var.EmployeeAddress);

writer.WriteEndElement();

}

writer.WriteEndElement();

writer.WriteEndDocument();

writer.Flush();

writer.Close();

result = stream.ToArray();

}

return result;

}

 

大家也知道，DataSet中的数据可以直接序列化成xml，通过dataSet.GetXml()，然后转化为binary即可。

 

XML的VARBINARY类型作为参数，批量删除的存储过程：

 

1: CREATE PROCEDURE [dbo].[_Employee_BulkDelete] 

2: ( 

3:  @EmployeeList VARBINARY(MAX)

4: ) 

5: AS 

6:  

7:  --XML ----

8:  DECLARE @EmployeeListXML XML;

9:  

  10:  -- TABLE to store XML records ----

  11:  DECLARE @TempEmployees TABLE

  12:  (

  13:EmployeeID BIGINT NULL,

  14:EmployeeName NVARCHAR(512) NULL DEFAULT(''),

  15:EmployeeAddress NVARCHAR(512) NULL DEFAULT('')

  16:  )

17: 

  18:  -- Get XML from binary stream -----

  19:  SET @EmployeeListXML = CONVERT(XML, @EmployeeList);

20: 

  21:  -- Fill to table-------

  22:  INSERT INTO @TempEmployees 

  23:  ( 

  24:EmployeeID,

  25:EmployeeName,

  26:EmployeeAddress

  27:  ) 

  28:  SELECT 

  29:nref.value('@id', 'BIGINT'),

  30:nref.value('@name', 'NVARCHAR(512)'),

  31:nref.value('@address', 'NVARCHAR(512)')

  32:  FROM  

  33:@EmployeeListXML.nodes('/Employees/Employee') R(nref)

34: 

  35:  --- Delete ----Maybe more complicated routine here !----------

36: 

  37:  DELETE [dbo].[TempEmployees]

  38:  FROM [dbo].[TempEmployees] AS T1

  39: INNER JOIN @TempEmployees AS T2 

  40: ON (T1.EmployeeID = T2.EmployeeID) 

  41:  WHERE (EmployeeSalary > 500000)

 

最后，如果想进一步优化该存储过程的效率，可以优化索引，使用临时表等。

------- 批量插入可以用SqlBulkCopy 参考：/article/5386412.html