我正在尝试创建一个 SQL 语句，该语句允许我删除表中比最合适的日期更早的所有行，同时保留最新的。这正在用于我正在从事的项目。我正在从 MS Access 数据库中获取数据并将该数据拖到 oracle 表中。该程序正在构建到我在 Visual Studio 2008 C# 中创建的 Windows 服务应用程序中，以便我可以让它定期运行以获取最新信息。
我只需要弄清楚要添加到我的代码中的更多内容：
想办法从我的 Oracle 表中删除那些旧行
告诉我的服务每隔一小时或 2 次运行一次
检查连接错误、丢失文件等。
对于我的主要问题和其他步骤的任何帮助将不胜感激。
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Diagnostics;
using System.Linq;
using System.ServiceProcess;
using System.Text;
using System.Data.OracleClient;
using System.Data.SqlClient;
using System.IO;
using System.Data.Odbc;
namespace GasReportservice
{
public partial class GasReportService : ServiceBase
{
public GasReportService()
{
InitializeComponent();
if (!System.Diagnostics.EventLog.SourceExists("MySource"))
{
System.Diagnostics.EventLog.CreateEventSource("MySource", "MyNewLog");
}
eventLog1.Source = "MySource";
eventLog1.Log = "MyNewLog";
}
protected override void OnStart(string[] args)
{
eventLog1.WriteEntry("In OnStart");
string connectionString = "Dsn=Gas_meter";
string col0 = "";
string col1 = "";
string col2 = "";
string col3 = "";
string col4 = "";
string col5 = "";
string col6 = "";
string col7 = "";
string col8 = "";
OdbcConnection DbConnection = new OdbcConnection(connectionString);
OdbcCommand DbCommand = DbConnection.CreateCommand();
DbConnection.Open();
DbCommand.CommandText = "SELECT DateTime, S1Flow, S2Flow, S3Flow, S4Flow, S1FlowTotal, S2FlowTotal, S3FlowTotal, S4FlowTotal FROM CommonStation WHERE Format(DateTime, 'mm/dd/yyyy') >=(select Format(max(DateTime),'mm/dd/yyyy') from CommonStation)";
OdbcDataReader DbReader = DbCommand.ExecuteReader();
int fCount = DbReader.FieldCount;
/*
for (int i = 0; i < fCount; i++)
{
String fName = DbReader.GetName(i);
Console.Write(fName + "\t");
}
*/
try
{
while (DbReader.Read())
{
string connString = "DSN=Gas_meter_proj;Uid=cm;Pwd=cmdev123";
OdbcConnection conn = new OdbcConnection(connString);
string sqlins = @"insert into Commonstation(CommStatDate_Time, S1_Flow, S2_Flow, S3_Flow, S4_Flow, S1_Flow_Total, S2_Flow_Total, S3_Flow_Total, S4_Flow_Total ) values (to_date('" + col0 + "', 'MM/DD/YYYY HH:MI:SS AM' ),to_number('" + col1 + "'), to_number('" + col2 + "'), to_number('" + col3 + "'), to_number('" + col4 + "'),to_number('" + col5 + "'),to_number('" + col6 + "'),to_number('" + col7 + "'),to_number('" + col8 + "'))";
OdbcCommand cmdnon = new OdbcCommand(sqlins, conn);
cmdnon.Parameters.Add(col0, OdbcType.DateTime);
cmdnon.Parameters.Add(col1, OdbcType.Numeric);
cmdnon.Parameters.Add(col2, OdbcType.Numeric);
cmdnon.Parameters.Add(col3, OdbcType.Numeric);
cmdnon.Parameters.Add(col4, OdbcType.Numeric);
cmdnon.Parameters.Add(col5, OdbcType.Numeric);
cmdnon.Parameters.Add(col6, OdbcType.Numeric);
cmdnon.Parameters.Add(col7, OdbcType.Numeric);
cmdnon.Parameters.Add(col8, OdbcType.Numeric);
conn.Open();
col0 = DbReader["DateTime"].ToString();
col1 = DbReader["S1Flow"].ToString();
col2 = DbReader["S2Flow"].ToString();
col3 = DbReader["S3Flow"].ToString();
col4 = DbReader["S4Flow"].ToString();
col5 = DbReader["S1FlowTotal"].ToString();
col6 = DbReader["S2FlowTotal"].ToString();
col7 = DbReader["S3FlowTotal"].ToString();
col8 = DbReader["S4FlowTotal"].ToString();
int rowsAffected = cmdnon.ExecuteNonQuery();
conn.Close();
Console.WriteLine(rowsAffected);
}
}
catch (Exception ex)
{
Console.WriteLine(ex.ToString());
}
finally
{
DbReader.Close();
DbCommand.Dispose();
DbConnection.Close();
}
}
protected override void OnContinue()
{
eventLog1.WriteEntry("My service has resumed action.");
}
protected override void OnPause()
{
eventLog1.WriteEntry("My service has been paused.");
}
protected override void OnStop()
{
eventLog1.WriteEntry("My service has been stopped.");
}
}
}