定义可在页面范围内访问的变量

Question

大家早上好，

我正在研究 vb.net。目的是使 CodeFile 运行一些 sql 查询，然后在页面加载时将值作为 sqldatasource 查询参数返回到网页。

我有以下 vb 代码

Partial Class Consult
Inherits Page
Public totalCount As Integer = "0"
'*******Here i declare the variable***************    
Public Property PatNo() As String
Get
Return ViewState("PatNo")
End Get
Set(ByVal value As String)
ViewState("PatNo") = value
End Set
End Property
Public PatNam As String = "abc"
Public ConID As String = "abc"
Public TreatType As String = "abc"
Public HPC As Char = "abc"
Public LvTyp As RadioButtonList

Protected Sub Page_Load(ByVal sender As Object, ByVal e As EventArgs) Handles Me.Load
Me.PatNo = Request.QueryString("pNo")
Session("PatientNo") = PatNo
Dim ConsultationID As String = Request.QueryString("consultID")
ConID = ConsultationID
Response.Write(PatNo)
Dim constr As String = ConfigurationManager.ConnectionStrings("DefaultConnection").ConnectionString
Using con As New SqlConnection(constr)
'**********BELOW LINE CAUSES ERROR**************
Dim query As String = "SELECT * FROM hPatients WHERE pNO=@PatNo" 
query += "SELECT * FROM hPatients WHERE pNO='001/000034824'"
Using cmd As New SqlCommand(query)
cmd.Parameters.Add("@PatNo", SqlDbType.NVarChar).Value = PatNo
Using sda As New SqlDataAdapter()
cmd.Connection = con
sda.SelectCommand = cmd
Using ds As New DataSet()
sda.Fill(ds)
gvPatientInfo.DataSource = ds.Tables(0)
'Return ds.Tables(0).Rows(0).Item(2)
'Response.Write(ds.Tables(0).Rows(0).Item(2))
gvPatientInfo.DataBind()
gvClientInfo.DataSource = ds.Tables(1)
gvClientInfo.DataBind()
End Using
End Using
End Using
End Using
If Not Me.IsPostBack Then
'Dim di As DataInfo = Me.GetInfo()

'Populating a DataTable from database.
Dim dt As DataTable = Me.GetData()
'Response.Write(ConID + " " + PatNo)
'Building an HTML string.
Dim html As New StringBuilder()
'Table start.
html.Append("<table border = '1' class = 'table'>")
'Building the Header row.
html.Append("<tr>")
For Each column As DataColumn In dt.Columns
html.Append("<th>")
html.Append(column.ColumnName)
html.Append("</th>")
Next
html.Append("</tr>")
'Building the Data rows.
For Each row As DataRow In dt.Rows
html.Append("<tr>")
For Each column As DataColumn In dt.Columns
html.Append("<td>")
html.Append(row(column.ColumnName))
html.Append("</td>")
Next
html.Append("</tr>")
Next
'Table end.
html.Append("</table>")
'Append the HTML string to Placeholder.
PlaceHolder1.Controls.Add(New Literal() With { _
.Text = html.ToString() _
})
End If
End Sub

我得到的错误是

Must declare the scalar variable "@PatNo".

此错误发生在获取变量以在 page_load 函数中执行查询的第一步中。

第二步是获取查询结果并在网页上使用。

有人，任何人，请帮忙

!!.

Answer 1

我认为问题出在这条线上：

cmd.Parameters.Add("PatNo", SqlDbType.NVarChar).Value = PatNo

将名称从"PatNo"更改为"@PatNo"，它应该可以工作。