根据表单中的值更改SQL Query

我正试图使我的SQL查询根据哪些值已在表单中输入/选择更改。

代码如下:

var var_db = Database.Open("Intranet");
var var_ticketID = "";
var var_department = "";
var var_ticketType = "";
var var_priority = "";
var var_ticketStatus = "";
var var_userAssigned = "";
var var_selectStatement = "SELECT Ticket_ID AS [Ticket], Logged_Date AS [Created], Ticket_Type AS [Ticket Type], Department, Priority, Forename, Surname, Ticket_Status AS [Status], Completed_Date AS [Completed], User_Assigned AS [User], Ticket_Subject AS [Subject] FROM Ticket_Data";
List<string> whereConditions = new List<string>();
if(!Request.QueryString["TicketNumber"].IsEmpty() ) {
    var_ticketID = Request.QueryString["TicketNumber"];
    whereConditions.Add("Ticket_ID = " + var_ticketID);
}
if(!Request.QueryString["Department"].IsEmpty() ) {
    var_department = Request.QueryString["Department"];
    whereConditions.Add("Department = " + var_department);
}
if(!Request.QueryString["TicketType"].IsEmpty() ) {
    var_ticketType = Request.QueryString["TicketType"];
    whereConditions.Add("Ticket_Type = " + var_ticketType);
}
if(!Request.QueryString["Priority"].IsEmpty() ) {
    var_priority = Request.QueryString["Priority"];
    whereConditions.Add("Priority = " + var_priority);
}
if(!Request.QueryString["Status"].IsEmpty() ) {
    var_ticketStatus = Request.QueryString["Status"];
    whereConditions.Add("Ticket_Status = " + var_ticketStatus);
}
if(!Request.QueryString["UserAssigned"].IsEmpty() ) {
    var_userAssigned = Request.QueryString["UserAssigned"];
    whereConditions.Add("User_Assigned = " + var_userAssigned);
}
var var_selectCommand = var_selectStatement + " WHERE " + string.Join(" AND ", whereConditions) + " ORDER BY LoggedDate DESC";
var var_selectedData = var_db.Query(var_selectCommand);
var var_grid = new WebGrid(source: var_selectedData, defaultSort: "Status", rowsPerPage:10);

这是标记。

<div id="header"><h2>Tickets</h2></div>
<div id="content">
<form method="get">
    <table>
        <tr><td>Ticket Number</td><td><input type="text" class="field" id="ticket_number" name="TicketNumber" ></td></tr>
        <tr><td>Department</td><td>
            <select class="field" id="department" name="Department" onchange="myFunction()" >
                <option value="">Please choose...</option>
                <option value="Department1">Department1</option>
                <option value="Department2">Department2</option>
                <option value="Department3">Department3</option>
                <option value="Department4">Department4</option>
                <option value="Department5">Department5</option>
                <option value="Department6">Department6</option>
            </select></td></tr>
        <tr><td>Ticket Type</td><td>
            <select class="field" id="ticket_type" name="TicketType" onchange="myFunction()" >
                <option value="">Please choose...</option>
                <option value="Change Request">Change Request</option>
                <option value="Fault">Fault</option>
            </select></td></tr>
        <tr><td>Priority</td><td>
            <select class="field" id="priority" name="Priority" onchange="myFunction()" >
                <option value="">Please choose...</option>
                <option value="Low">Low</option>
                <option value="Medium">Medium</option>
                <option value="High">High</option>
            </select></td></tr>
        <tr><td>Status</td><td>
            <select class="field" id="status" name="Status" onchange="myFunction()" >
                <option value="">Please choose...</option>
                <option value="Open">Open Tickets</option>
                <option value="Closed">Closed Tickets</option>
                <option value="%">All Tickets</option>
            </select></td></tr>
        <tr><td>User Assigned</td><td>
            <select class="field" id="user_assigned" name="UserAssigned" onchange="myFunction()" >
                <option value="">Please choose...</option>
                <option value="User1">User1</option>
                <option value="User2">User2</option>
                <option value="User3">User3</option>
                <option value="User4">User4</option>
                <option value="%">All Users</option>
                <option value="Unassigned">Unassigned</option>
            </select></td></tr>
    </table>
    <p><input type="submit" value="Search" ></p>
</form>
<div>
    @var_grid.GetHtml(
        tableStyle: "grid",
        headerStyle: "head",
        columns: var_grid.Columns(
            var_grid.Column("Ticket", format: @<a href="~/ticket_details?id=@item.Ticket">@item.Ticket</a>),
            var_grid.Column("Created"),
            var_grid.Column("Ticket Type"),
            var_grid.Column("Priority"),
            var_grid.Column("Subject"),
            var_grid.Column("Department"),
            var_grid.Column("Status"),
            var_grid.Column("Completed"),
            var_grid.Column("User")
       )
    )
</div>

不幸的是它不工作。有人能帮我一下吗?

CREATE PROC dbo.SomeProcName
    @param1 int = null,
    @param2 varchar(20) = null
AS
    SELECT * FROM someTable
    WHERE
        (@param1 = NULL OR column1 = @param1) AND
        (@param2 = NULL OR column2 = @param2)