SQL SERVER CLR Trigger功能

通过在 Microsoft SQL Server 中托管 CLR（称为 CLR 集成），开发人员可以在托管代码中编写存储过程、触发器、用户定义函数、用户定义类型和用户定义聚合函数, 改变了以前只能通过T-SQL语言来实现这些功能的局面。因为托管代码在执行之前会编译为本机代码，所以，在有些方案中可以大大提高性能。

1. 编写C#代码，编译成.NET 3.5的dll

public class Program
{
    [SqlTrigger(Name = @"UsersAudit", Target = "[dbo].[users]", Event = "FOR INSERT")]
    public static void UsersAudit()
    {
        SqlContext.Pipe.Send("UsersAudit start");
        // Get the trigger context.
        string userName;
        string realName;
        SqlCommand command;
        SqlTriggerContext triggContext = SqlContext.TriggerContext;
        SqlDataReader reader;

        switch (triggContext.TriggerAction)
        {
            case TriggerAction.Insert:

                // Retrieve the connection that the trigger is using.
                using (SqlConnection connection
                   = new SqlConnection(@"context connection=true"))
                {
                    connection.Open();

                    // Get the inserted row.
                    command = new SqlCommand(@"SELECT * FROM INSERTED;",
                                             connection);

                    // Get the user name and real name of the inserted user.
                    reader = command.ExecuteReader();
                    reader.Read();
                    userName = (string)reader[0];
                    realName = (string)reader[1];
                    reader.Close();

                    // Insert the user name and real name into the auditing table.
                    command = new SqlCommand(@"INSERT [dbo].[UserNameAudit] (userName, realName) "
                             + @"VALUES (@userName, @realName);", connection);

                    command.Parameters.Add(new SqlParameter("@userName", userName));
                    command.Parameters.Add(new SqlParameter("@realName", realName));

                    command.ExecuteNonQuery();

                }

                break;
        }

        SqlContext.Pipe.Send("UsersAudit end");
    }


    [Microsoft.SqlServer.Server.SqlProcedure]
    public static void HelloWorld(out string text)
    {
        SqlContext.Pipe.Send("Hello world!" + Environment.NewLine);
        text = "Hello world!";
    }
}

2. SMSS中选择“可编程性” -> "程序集"->“右键”-》“新建程序集”，将编译的dll注册

3.打开SMSS查询窗口，执行一下的sql语句将触发器和存储过程注册。注意程序集名称和命名空间名称的格式。

CREATE PROCEDURE hello  
@i nchar(25) OUTPUT  
AS  
EXTERNAL NAME SqlTriggerContextTest.Program.HelloWorld  
GO
-- if the HelloWorldProc class is inside a namespace (called MyNS),  
-- the last line in the create procedure statement would be  
-- EXTERNAL NAME helloworld.[MyNS.HelloWorldProc].HelloWorld  

CREATE TRIGGER UsersAudit 
ON [dbo].[users]
AFTER INSERT, UPDATE
AS
EXTERNAL NAME SqlTriggerContextTest.Program.UsersAudit  
GO

4. 可以执行sql语句查看效果　

运行 select * from sys.assemblies 可以查看注册的程序集

如果dll中需要使用TCP功能，那么程序集必须签名。

参考：https://www.cnblogs.com/alexcodinglife/articles/5563148.html

SQL SERVER CLR Trigger功能

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