WinForms中可能用到辅助类，DBHelper-数据库的打开和关闭

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Data.SqlClient;
using System.Data;
namespace DBHelper
{
class DBHelper
{
private string connString = "Data Source=.;Initial Catalog=MySchool;User Id=sa;Pwd=ok";
private SqlConnection connection;
//connection 对象
public SqlConnection Connection
{
get
{
if (connection == null)
{
connection = new SqlConnection(connString);
}
return connection;
}
}
//打开连接
public void OpenConnection()
{
//如果状态为关闭，则打开连接
if (Connection.State == ConnectionState.Closed)
{
Connection.Open();
}
//否则如果正在使用，则先关闭再打开
else if (Connection.State == ConnectionState.Broken)
{
Connection.Close();
Connection.Open();
}
}
//关闭连接
public void CloseConnection()
{
if (Connection.State == ConnectionState.Open || Connection.State == ConnectionState.Broken)
{
Connection.Close();
}
}
}
}