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我正在使用實體框架，現在我正在保存兩個作業，並希望將它們展示給我的gridview。我如何清除會話？
在這裏，我將它們保存到我的數據庫表，並顯示他們在GridView： 
這裏的代碼：
protected void ButtonAddAssignmentClick(object sender, EventArgs e)
{
Session.Remove("DataTable");
//Add to DB and show in gridview
using (var db = new KnowItCvdbEntities())
{
SPWeb theSite = SPControl.GetContextWeb(Context);
SPUser theUser = theSite.CurrentUser;
string strUserName = theUser.LoginName;
var theEmplAssignment = (
from p
in db.EMPLOYEES
where p.username == strUserName
select p).FirstOrDefault();
_emp = theEmplAssignment;
if (_emp != null)
{
//Create assignment
var myAssignment = new EMPLOYEES_ASSIGNMENT
{
assignment_id = new Random().Next(),
employee_id = _emp.employee_id,
reference_name = TextBoxReference.Text,
company_name = TextBoxCompanyName.Text,
sector = TextBoxSector.Text,
area = TextBoxArea.Text,
from_date = TextBoxFromDate.Text,
to_date = TextBoxToDate.Text,
description = TextBoxDesc.Text,
};
//Create assignment tools
for (int i = 0; i < ListBoxAssignmentTools.Items.Count; i++)
{
var myTool = new ASSIGNMENT_TOOLS
{
assignment_tools_id = new Random().Next(),
assignment_id = myAssignment.assignment_id,
employee_id = myAssignment.employee_id,
tool_name = ListBoxAssignmentTools.Items[i].ToString()
};
myAssignment.ASSIGNMENT_TOOLS.Add(myTool);
}
//Create assignment technology
for (int i = 0; i < ListBoxAssignmentTechnology.Items.Count; i++)
{
var myTech = new ASSIGNMENT_TECHNOLOGY
{
assignment_technology_id = new Random().Next(),
assignment_id = myAssignment.assignment_id,
employee_id = myAssignment.employee_id,
technology_name = ListBoxAssignmentTechnology.Items[i].ToString()
};
myAssignment.ASSIGNMENT_TECHNOLOGY.Add(myTech);
}
//Add assignment to db
_emp.EMPLOYEES_ASSIGNMENT.Add(myAssignment);
db.SaveChanges();
//Populate gridview
var dt = new DataTable();
if (Session["DataTable"] != null)
{
dt = (DataTable)Session["DataTable"];
}
else
{
dt.Columns.Add("Company name");
dt.Columns.Add("Sector");
dt.Columns.Add("Area");
dt.Columns.Add("From");
dt.Columns.Add("To");
dt.Columns.Add("Tools");
dt.Columns.Add("Technology");
dt.Columns.Add("Description");
dt.Columns.Add("Reference");
dt.Rows.Clear();
}
DataRow dr = dt.NewRow();
dr["Company name"] = TextBoxCompanyName.Text;
dr["Sector"] = TextBoxSector.Text;
dr["Area"] = TextBoxArea.Text;
dr["From"] = TextBoxFromDate.Text;
dr["To"] = TextBoxToDate.Text;
dr["Description"] = TextBoxDesc.Text;
dr["Reference"] = TextBoxReference.Text;
string sToolsValue = string.Empty;
for (int i = 0; i < ListBoxAssignmentTools.Items.Count; i++)
{
sToolsValue += ListBoxAssignmentTools.Items[i] + " ";
}
dr["Tools"] = sToolsValue;
string sTechValue = string.Empty;
for (int i = 0; i < ListBoxAssignmentTechnology.Items.Count; i++)
{
sTechValue += ListBoxAssignmentTechnology.Items[i] + " ";
}
dr["Technology"] = sTechValue;
dt.Rows.Add(dr);
Session["DataTable"] = dt;
//Add to gridview
GridViewShowAssignments.DataSource = dt;
GridViewShowAssignments.DataBind();
TextBoxCompanyName.Text = string.Empty;
TextBoxArea.Text = string.Empty;
TextBoxSector.Text = string.Empty;
TextBoxFromDate.Text = string.Empty;
TextBoxToDate.Text = string.Empty;
TextBoxDesc.Text = string.Empty;
TextBoxReference.Text = string.Empty;
ListBoxAssignmentTools.Items.Clear();
ListBoxAssignmentTechnology.Items.Clear();
}
}
}
而且我使用的頁面加載，檢索的方法在當前登錄用戶上的所有分配並在gridview上顯示它。 但是，gridview填充重複！我懷疑我必須在頁面加載時清除會話，但我不知道如何去做。 
的方法的代碼：
//Get assignment from db and populate gridview
private void GetEmployeeAssignment(EMPLOYEE theEmpl)
{
Session.Remove("DataTable");
using (var db = new KnowItCvdbEntities())
{
if (_emp != null)
{
var assignmentList = from p in db.EMPLOYEES_ASSIGNMENT.AsEnumerable()
join at in db.ASSIGNMENT_TOOLS.AsEnumerable() on p.assignment_id equals at.assignment_id
join ate in db.ASSIGNMENT_TECHNOLOGY.AsEnumerable() on p.assignment_id equals ate.assignment_id
where p.employee_id == theEmpl.employee_id
select new EmployeeAssignmentInfo
{
CompanyName = p.company_name,
AssignmentId = p.assignment_id,
Area = p.area,
From = p.from_date,
To = p.to_date,
Description = p.description,
Sector = p.sector,
Reference = p.reference_name,
ToolName = at.tool_name,
AssignmentToolsId = at.assignment_tools_id,
TechnologyName = ate.technology_name,
AssignmentTechnologyId = ate.assignment_technology_id
};
foreach (var vAssignment in assignmentList)
{
//Populate gridview
var dt = new DataTable();
if (Session["DataTable"] != null)
{
dt = (DataTable)Session["DataTable"];
}
else
{
dt.Columns.Add("Company name");
dt.Columns.Add("Sector");
dt.Columns.Add("Area");
dt.Columns.Add("From");
dt.Columns.Add("To");
dt.Columns.Add("Tools");
dt.Columns.Add("Technology");
dt.Columns.Add("Description");
dt.Columns.Add("Reference");
dt.Rows.Clear();
}
DataRow dr = dt.NewRow();
dr["Company name"] = vAssignment.CompanyName;
dr["Sector"] = vAssignment.Sector;
dr["Area"] = vAssignment.Area;
dr["From"] = vAssignment.From;
dr["To"] = vAssignment.To;
dr["Description"] = vAssignment.Description;
dr["Reference"] = vAssignment.Reference;
dr["Tools"] = vAssignment.ToolName + " ";
dr["Technology"] = vAssignment.TechnologyName + " ";
dt.Rows.Add(dr);
Session["DataTable"] = dt;
GridViewShowAssignments.DataSource = dt;
GridViewShowAssignments.DataBind();
}
}
else
{
LabelPleaseRegister.Visible = true;
LabelPleaseRegister.Text = "Please register your personal information";
PanelRegisterCv.Visible = false;
PanelRegisterPersonalInfo.Visible = false;
}
}
}
頁負載：
protected void Page_Load(object sender, EventArgs e)
{
SPWeb theSite = SPControl.GetContextWeb(Context);
SPUser theUser = theSite.CurrentUser;
string strUserName = theUser.LoginName;
LabelUsername.Text = strUserName;
if (!IsPostBack)
{
_emp = GetEmployee(strUserName);
GetEmployeeAssignment(_emp);
}
}