C# 如何比较CLR insert和update触发器中的新旧字段值

我们正在考虑使用一些SQL CLR触发器来填充某些表的审核日志，我知道如何在服务器中注册CLR程序集和触发器，当我知道要查找哪些列以及是否必须在审核日志表中插入新记录时，所有这些都可以正常工作

现在，我们希望它独立于受监视的表模式，这样我们就不需要在添加或重命名到源表的每个新列上编辑和重新部署触发器，我希望在我的审计表中保留一些简单的内容，例如包含更改快照的n XML列，例如：

<AuditEntry ObjectName='TableName' ObjectId='1'>
    <Field='Firstname'>
        <OldValue>David</OldValue>
        <NewValue>Davide</NewValue>
    </Field>
    <Field='Email'>
        <OldValue/>
        <NewValue>aaa.b@gmail.com</NewValue>
    </Field>
</AuditEntry>

大卫
达维德
aaa。b@gmail.com

这个XML只是一个例子，我只需要了解如何编写触发器C#代码，这样它就可以一个字段一个字段地比较旧行和新行，得到旧值和新值，然后我就知道如何将其转储到XML文档中

非常感谢，

---

Davide.

我做了一些测试，我自己解决了这个问题，这里是为了分享整个故事；-）

1）.NET SQL CLR触发器，仅一个将侦听两个表的触发器，唯一的假设是监视的表有一个名为Id的标识列

using System.Data.SqlClient;
using System.Xml;
using Microsoft.SqlServer.Server;

namespace Axis.CLR.SampleObjects
{
    using System;
    using System.Data;
    using System.Data.SqlTypes;
    using System.Text;

    public partial class AuditTrigger
    {
        public const string GetTableContextStatement =
            "SELECT object_name(resource_associated_entity_id) FROM sys.dm_tran_locks WHERE request_session_id = @@spid and resource_type = 'OBJECT'";

        [SqlTrigger(Name = "UserNameAudit", Target = "Users", Event = "FOR INSERT")]
        public static void UserNameAudit()
        {
            SqlTriggerContext triggContext = SqlContext.TriggerContext;

            //SqlPipe sqlP = SqlContext.Pipe;

            using (SqlConnection conn = new SqlConnection("context connection=true"))
            using (SqlCommand sqlComm = conn.CreateCommand())
            {
                conn.Open();

                // Gets a reference to the affected table name
                string tableName = string.Empty;
                using (SqlCommand cmd = new SqlCommand(GetTableContextStatement, conn))
                {
                    tableName = cmd.ExecuteScalar().ToString();
                }

                // STORING INSERT AUDIT

                if (triggContext.TriggerAction == TriggerAction.Insert)
                {
                    #region handling INSERT action

                    sqlComm.CommandText = "SELECT * from INSERTED";
                    var reader = sqlComm.ExecuteReader();

                    if (reader.Read())
                    {
                        XmlDocument finalDocument = new XmlDocument();

                        XmlNode rootElement = finalDocument.CreateNode(XmlNodeType.Element, tableName, string.Empty);

                        XmlAttribute newAttribute = finalDocument.CreateAttribute("Id");
                        newAttribute.Value = reader.GetInt64(reader.GetOrdinal("Id")).ToString();
                        rootElement.Attributes.Append(newAttribute);

                        newAttribute = finalDocument.CreateAttribute("Operation");
                        newAttribute.Value = "INSERT";
                        rootElement.Attributes.Append(newAttribute);

                        finalDocument.AppendChild(rootElement);

                        XmlNode createdElement = finalDocument.CreateNode(XmlNodeType.Element, "Fields", string.Empty);

                        for (int i = 0; i < reader.FieldCount; i++)
                        {
                            XmlNode fieldElement = finalDocument.CreateNode(XmlNodeType.Element, reader.GetName(i), string.Empty);

                            if (reader.IsDBNull(i))
                            {
                                fieldElement.InnerText = "NULL";
                            }
                            else
                            {
                                fieldElement.InnerText = reader.GetValue(i).ToString();
                            }

                            createdElement.AppendChild(fieldElement);
                        }

                        // Node was added
                        rootElement.AppendChild(createdElement);

                        // Adds the Audit

                        sqlComm.CommandText = "[dbo].[AddAuditTrail]";
                        sqlComm.CommandType = CommandType.StoredProcedure;

                        SqlParameter xmlParamA = new SqlParameter("@ObjectId", SqlDbType.BigInt);
                        xmlParamA.Value = reader.GetInt64(reader.GetOrdinal("Id"));
                        sqlComm.Parameters.Add(xmlParamA);

                        reader.Close();

                        sqlComm.Parameters.AddWithValue("@ObjectName", tableName);

                        SqlParameter xmlParamB = new SqlParameter("@TraceXML", SqlDbType.Xml);
                        xmlParamB.Value = new SqlXml(new XmlTextReader(finalDocument.OuterXml, XmlNodeType.Document, null));
                        sqlComm.Parameters.Add(xmlParamB);

                        sqlComm.Parameters.AddWithValue("@AuditType", "INSERT");

                        sqlComm.ExecuteNonQuery();

                        //sqlP.Send(string.Format("Generated AFTER INSERT XML is: '{0}'", finalDocument.OuterXml));
                    }

                    #endregion handling INSERT action
                }
                else if (triggContext.TriggerAction == TriggerAction.Update)
                {
                    #region handling UPDATE action

                    DataSet values = new DataSet();
                    SqlDataAdapter adapter = new SqlDataAdapter(sqlComm);

                    sqlComm.CommandText = "SELECT * from INSERTED";
                    adapter.Fill(values, "INSERTED");

                    sqlComm.CommandText = "SELECT * from DELETED";
                    adapter.Fill(values, "DELETED");

                    StringBuilder builder = new StringBuilder();

                    builder.Append("<Fields>");

                    int recordId = 0;

                    for (int i = 0; i < values.Tables["INSERTED"].Columns.Count; i++)
                    {
                        string colName = values.Tables["INSERTED"].Columns[i].ColumnName;

                        if (colName.ToLower().Equals("id"))
                        {
                            recordId = Convert.ToInt32(values.Tables["DELETED"].Rows[0][i]);

                            builder.AppendFormat("<Id value='{0}' />", recordId);
                        }

                        // if both nulls or both the same, no audit needed...

                        if (values.Tables["INSERTED"].Rows[0].IsNull(i) && values.Tables["DELETED"].Rows[0].IsNull(i))
                        {
                            continue;
                        }

                        if (values.Tables["INSERTED"].Rows[0][i].Equals(values.Tables["DELETED"].Rows[0][i]))
                        {
                            continue;
                        }

                        builder.AppendFormat("<{0}>", colName);

                        // DUMPING OLD VALUE
                        builder.Append("<OldValue>");

                        if (values.Tables["DELETED"].Rows[0].IsNull(i))
                        {
                            builder.Append("NULL");
                        }
                        else
                        {
                            builder.Append(values.Tables["DELETED"].Rows[0][i]);
                        }

                        builder.Append("</OldValue>");

                        // DUMPING NEW VALUE
                        builder.Append("<NewValue>");

                        if (values.Tables["INSERTED"].Rows[0].IsNull(i))
                        {
                            builder.Append("NULL");
                        }
                        else
                        {
                            builder.Append(values.Tables["INSERTED"].Rows[0][i]);
                        }

                        builder.Append("</NewValue>");

                        builder.AppendFormat("</{0}>", colName);
                    }

                    builder.Append("</Fields>");

                    builder.Insert(0, string.Format("<{0} Id='{1}' Operation='{2}'>", tableName, recordId, "UPDATE"));
                    builder.AppendFormat("</{0}>", tableName);

                    // Adds the Audit

                    sqlComm.CommandText = "[dbo].[AddAuditTrail]";
                    sqlComm.CommandType = CommandType.StoredProcedure;

                    SqlParameter xmlParamA = new SqlParameter("@ObjectId", SqlDbType.BigInt);
                    xmlParamA.Value = recordId;
                    sqlComm.Parameters.Add(xmlParamA);

                    sqlComm.Parameters.AddWithValue("@ObjectName", tableName);

                    SqlParameter xmlParamB = new SqlParameter("@TraceXML", SqlDbType.Xml);
                    xmlParamB.Value = new SqlXml(new XmlTextReader(builder.ToString(), XmlNodeType.Document, null));
                    sqlComm.Parameters.Add(xmlParamB);

                    sqlComm.Parameters.AddWithValue("@AuditType", "UPDATE");

                    sqlComm.ExecuteNonQuery();

                    //sqlP.Send(string.Format("Generated AFTER UPDATE XML is: '{0}'", builder.ToString()));

                    #endregion handling UPDATE action
                }
            }
        }
    }
}

3）这里是我的审计表的create语句

CREATE TABLE [dbo].[AuditTrail]
(
    [Id] [bigint] IDENTITY(1,1) NOT NULL,
    [AuditDate] [datetime2](7) NOT NULL,
    [UserName] [nvarchar](64) NOT NULL,
    [ObjectId] [bigint] NOT NULL,
    [ObjectName] [nvarchar](128) NOT NULL,
    [TraceXML] [xml] NOT NULL,
    [TraceSize] [int] NOT NULL,
    [AuditType] [nvarchar](16) NOT NULL,
 CONSTRAINT [PK_AuditTrail] PRIMARY KEY CLUSTERED ( [Id] ASC )
)
GO

ALTER TABLE [dbo].[AuditTrail] ADD  CONSTRAINT [DF_AuditTrail_AuditDate]  DEFAULT (sysutcdatetime()) FOR [AuditDate]
GO

ALTER TABLE [dbo].[AuditTrail] ADD  CONSTRAINT [DF_AuditTrail_UserName]  DEFAULT (suser_sname()) FOR [UserName]
GO

4）这里是触发器调用的存储过程，用于在每次插入/更新时添加新的审核记录

CREATE PROCEDURE [dbo].[AddAuditTrail]
    @ObjectId bigint, 
    @ObjectName nvarchar(128),
    @TraceXML xml,
    @AuditType nvarchar(16)
AS
BEGIN
    -- SET NOCOUNT ON added to prevent extra result sets from
    -- interfering with SELECT statements.
    SET NOCOUNT ON;

    INSERT INTO [dbo].[AuditTrail] ([ObjectId], [ObjectName], [TraceXML], [TraceSize], [AuditType])
        VALUES (@ObjectId, @ObjectName, @TraceXML, DATALENGTH(@TraceXML), @AuditType)
END
GO

5）对于

插入和
更新，我的审核表的内容如下所示

<Users Id="51" Operation="INSERT">
  <Fields>
    <UserName>Davide</UserName>
    <Pass>Test</Pass>
    <Id>51</Id>
    <Email>NULL</Email>
  </Fields>
</Users>

<Users Id="51" Operation="UPDATE">
  <Fields>
    <Id value="51" />
    <Email>
      <OldValue>NULL</OldValue>
      <NewValue>@</NewValue>
    </Email>
  </Fields>
</Users>


达维德
试验
51
无效的
无效的
@

<Users Id="51" Operation="INSERT">
  <Fields>
    <UserName>Davide</UserName>
    <Pass>Test</Pass>
    <Id>51</Id>
    <Email>NULL</Email>
  </Fields>
</Users>

<Users Id="51" Operation="UPDATE">
  <Fields>
    <Id value="51" />
    <Email>
      <OldValue>NULL</OldValue>
      <NewValue>@</NewValue>
    </Email>
  </Fields>
</Users>