查询问题 各位帮帮忙 先谢谢啦
功能是在Form中的文本框中输入内容，点击查询按钮，把符合的内容显示在DataGrid中。上述功能实现只能查询一次，不会出现问题，当再重新输入内容再次查询时出现错误，不能实现查询了，问题在哪里？
请指教！谢谢了！

代码如下：
private   void   Form1_Load(object   sender,   System.EventArgs   e)
{
string   Connstr,SelectCmd;
Connstr= "Server=(local);Database=tester1;Trusted_Connection=SSPI ";
SelectCmd= "select*   From   EquipmentInformation   ORDER   by   id   desc ";

SqlConnection   Conn;
SqlDataAdapter   myAdapter;
DataSet   myDataSet=new   DataSet   ();
Conn=new   SqlConnection   (Connstr);

myAdapter=new   SqlDataAdapter   (SelectCmd,Conn);
myAdapter.Fill(myDataSet, "设备信息 ");


dataGrid1.DataSource=myDataSet;
dataGrid1.DataMember= "设备信息 ";

                                                        cbo1.Text   =   dataGrid1[0,   1].ToString();
  textBox2.Text   =   dataGrid1[0,2   ].ToString();
  textBox3.Text   =   dataGrid1[0,3   ].ToString();
  cbo2.Text   =   dataGrid1[0,4   ].ToString();
  textBox5.Text   =   dataGrid1[0,5   ].ToString();
  textBox6.Text   =   dataGrid1[0,6   ].ToString();
  textBox7.Text   =   dataGrid1[0,7   ].ToString();
}
 
private   int   CheckInt(string   str)
{
try
{
return   int.Parse   (str);
}
catch  
{
return   0;
}
}
private   void   btn8_Click(object   sender,   System.EventArgs   e)
{
     
string   Connstr,SelectCmd;
Connstr= "Server=(local);Database=tester1;Trusted_Connection=SSPI ";
SelectCmd= "select*   From   EquipmentInformation   Where   SubstationName= ' "+cbo1.Text   + " 'or   EquipmentID= ' "+CheckInt(textBox2.Text)+ " 'or   OperationID= ' "+CheckInt(textBox5.Text)+ " '   ORDER   by   id   desc ";;

SqlConnection   Conn;
SqlDataAdapter   myAdapter;
DataSet   myDataSet=new   DataSet   ();
Conn=new   SqlConnection   (Connstr);

myAdapter=new   SqlDataAdapter   (SelectCmd,Conn);
myAdapter.Fill(myDataSet, "设备信息 ");

cbo1.DataSource   =myDataSet;
cbo1.DisplayMember   = "设备信息.SubstationName ";

cbo2.DataSource   =myDataSet;
cbo2.DisplayMember   = "设备信息.TesterName ";

textBox2.DataBindings.Add   ( "text ",myDataSet, "设备信息.EquipmentID ");
textBox3.DataBindings.Add   ( "text ",myDataSet, "设备信息.VoltageGrade ");
textBox5.DataBindings.Add   ( "text ",myDataSet, "设备信息.OperationID ");
textBox6.DataBindings.Add   ( "text ",myDataSet, "设备信息.Modle ");
textBox7.DataBindings.Add   ( "text ",myDataSet, "设备信息.Data ");



dataGrid1.DataSource=myDataSet;
dataGrid1.DataMember= "设备信息 ";

}

错误如下：
未处理的“ Linq左连接+多条件解决方案