必须再次声明标量变量

Question

我有一个datagrid控件，我正在尝试根据在页面上输入参数的sql查询来填充该控件。我一直得到‘必须声明标量变量@epa1’，所以我有点迷失了方向。VB代码是：

     Dim DT As DataTable
    Dim DS As New DataSet()
    Dim conn As New SqlConnection("Data Source=azda-sql1a;Initial Catalog=pesticide;User ID=sa;Password=Sql@dm!n")
    Dim cmd As New SqlCommand
    Dim query As String
    Dim DA As SqlDataAdapter
    query = "select epa1, epa2, dist_nr as epa3, ai1, rei, rup from products where epa1 = @epa1 and epa2 = @epa2 and dist_nr = @epa3"

    cmd.CommandType = CommandType.Text
    cmd.CommandText = query
    cmd.Connection = conn
    cmd.Parameters.AddWithValue("@epa1", txtEPA1.Text)
    cmd.Parameters.AddWithValue("@epa2", txtEPA2.Text)
    cmd.Parameters.AddWithValue("@epa3", txtEPA3.Text)
    '\search for pesticides based on epa numbers
    'select BrandName,ActiveIngredient1 from NewProductsList where epa1=# and epa2=# and epa3=#
    If Me.txtEPA1.Text = "" Or Me.txtEPA2.Text = "" Or Me.txtEPA3.Text = "" Then
        Me.lblProductErrors.Text = "Please enter in all EPA numbers for accurate search, when in doubt enter Zero"
    End If
    cmd.Connection.Open()
    DA = New SqlDataAdapter(query, conn)

    DA.Fill(DS)
    DT = DS.Tables(0)
    conn.Close()

所以我假设所有3个变量，@epa1，@epa2和@epa3都没有声明，但是话又说回来，它们就在那里。有人能帮上忙吗？Thanks..have祝大家圣诞快乐！

Answer 1

您在Command上设置参数，然后使用query (不带参数)来初始化DataAdapter。

因此，不使用查询来初始化DataAdapter：

DA = New SqlDataAdapter(query, conn)

使用命令初始化它(已经设置了参数)：

DA = New SqlDataAdapter(cmd)