下午,所以我在这个问题上待了好几个小时,无法真正克服最后一个困难。以下是我正在编写的该程序的代码:
using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Diagnostics; using System.Data; using System.Data.SqlClient; using System.Configuration; namespace Test { class Program { static void Main() { EventLog alog = new EventLog(); alog.Log = "Application"; alog.MachineName = "."; foreach (EventLogEntry entry in alog.Entries) { SqlConnection connection1 = new SqlConnection(@"Data Source=.\sqlexpress;Initial Catalog=syslog2;Integrated Security=True"); SqlDataAdapter cmd = new SqlDataAdapter(); cmd.InsertCommand = new SqlCommand("INSERT INTO Application VALUES (@EventLog, @TimeGenerated, @EventType, @SourceName, @ComputerName, @InstanceId, @Message) "); cmd.InsertCommand.Parameters.Add("@EventLog",SqlDbType.VarChar).Value = alog.Log; cmd.InsertCommand.Parameters.Add("@TimeGenerated", SqlDbType.DateTime).Value = entry.TimeGenerated; cmd.InsertCommand.Parameters.Add("@EventType", SqlDbType.VarChar).Value = entry.EntryType; cmd.InsertCommand.Parameters.Add("@SourceName", SqlDbType.VarChar).Value = entry.Source; cmd.InsertCommand.Parameters.Add("@ComputerName", SqlDbType.VarChar).Value = entry.MachineName; cmd.InsertCommand.Parameters.Add("@InstanceId", SqlDbType.VarChar).Value = entry.InstanceId; cmd.InsertCommand.Parameters.Add("@Message", SqlDbType.VarChar).Value = entry.Message; connection1.Open(); cmd.InsertCommand.ExecuteNonQuery(); connection1.Close(); } } } }
该代码可以正常编译,没有错误或警告,但是当我运行它时,只要它到达cmd.InsertCommand.ExecuteNonQuery();就可以了。我收到以下错误:
ExecuteNonQuery:连接属性尚未初始化。
关于我错过的任何想法?
您需要将连接分配给SqlCommand,可以使用构造函数或属性:
SqlCommand
cmd.InsertCommand = new SqlCommand("INSERT INTO Application VALUES (@EventLog, @TimeGenerated, @EventType, @SourceName, @ComputerName, @InstanceId, @Message) "); cmd.InsertCommand.Connection = connection1;
我强烈建议对using-statement实现IDisposable类似的任何类型使用SqlConnection,它还会关闭连接:
using-statement
IDisposable
SqlConnection
using(var connection1 = new SqlConnection(@"Data Source=.\sqlexpress;Initial Catalog=syslog2;Integrated Security=True")) using(var cmd = new SqlDataAdapter()) using(var insertCommand = new SqlCommand("INSERT INTO Application VALUES (@EventLog, @TimeGenerated, @EventType, @SourceName, @ComputerName, @InstanceId, @Message) ")) { insertCommand.Connection = connection1; cmd.InsertCommand = insertCommand; //..... connection1.Open(); // .... you don't need to close the connection explicitely }
除此之外,你并不需要创建一个新的连接,并DataAdapter在每个条目foreach,即使创建,打开和关闭连接并 不能 意味着ADO.NET将创建,打开和关闭一个 物理 连接,但只是眺望用于可用连接的连接池。但是,这是不必要的开销。
DataAdapter
foreach