30分提问！不够+顶这有分！显示问题！请大伙来帮忙！SOS！！！
大概意思是这样的，查询某个人当月的数据！有两个DropDownList一个是选择“年份的”另一个是选择“月份的”选择好了然后单击Button在DataGrid中做显示！
源码如下：
string   Jgr   =   String.Empty;
private   void   Page_Load(object   sender,   System.EventArgs   e)
{
Jgr   =   Request.QueryString[ "Jgr "].ToString();
if(!IsPostBack)
{
SqlConnection   con   =   DataCon.DataJCon.JCon();
con.Open();
SqlCommand   cmd   =   new   SqlCommand( "Year_GetList ",con);
cmd.CommandType   =   CommandType.StoredProcedure;
SqlDataReader   sdr   =   cmd.ExecuteReader();
this.Nf.DataSource   =   sdr;
this.Nf.DataTextField   =   "YearName ";
this.Nf.DataValueField   =   "YearId ";
this.Nf.DataBind();
this.Nf.Items.Insert(0,new   ListItem( "—请选年份— ", "-1 "));
sdr.Close();

SqlCommand   cmmd   =   new   SqlCommand( "Month_GetList ",con);
cmmd.CommandType   =   CommandType.StoredProcedure;
SqlDataReader   sdz   =   cmmd.ExecuteReader();
this.Yf.DataSource   =   sdz;
this.Yf.DataTextField   =   "MonthName ";
this.Yf.DataValueField   =   "MonthId ";
this.Yf.DataBind();
this.Yf.Items.Insert(0,new   ListItem( "—请选月份— ", "-1 "));
sdz.Close();
con.Close();
}
}
private   void   YfCx_Click(object   sender,   System.EventArgs   e)
{
string   Jgsj   = " ' "+Nf.SelectedItem.Text+ "- "+Yf.SelectedItem.Text+ "-01 ' ";
SqlConnection   con   =   DataCon.DataJCon.JCon();
con.Open();
SqlDataAdapter   sda   =   new   SqlDataAdapter();
sda.SelectCommand   =   new   SqlCommand( "exec   Work_5500   "   +   Jgr   +   ", "   +   Jgsj,con);
DataSet   ds   =   new   DataSet();
sda.Fill(ds, "emp ");
this.DataGrid1.DataSource=ds.Tables[ "emp "];
this.DataGrid1.DataKeyField   =   "WorkId ";
this.DataGrid1.DataBind();
con.Close();
}

现在出现问题的地方是这句
string   Jgsj   = " ' "+Nf.SelectedItem.Text+ "- "+Yf.SelectedItem.Text+ "-01 ' ";
Nf和Yf获取的是数据库中的Text，也就好比2009-11-01
但是在数据库中每个月不指“-01日”现在查询到的全是-01日的情况，其它的比方-02         -03         -04     ......     -29       -30       -31     都查询不到！应该如何修改请高手帮着看看吧

------解决方案--------------------
string Jgsj = " ' "+Nf.SelectedItem.Text+ "- "+Yf.SelectedItem.Text+ "-01 ' ";
-----------------
Jgsj 这个变量显示的内容是什么呢？