Question

请帮我解决这个问题，我已经搜索了几个小时但无法解决。

这是我的代码：

Private Sub search_btn_Click(sender As Object, e As EventArgs) Handles search_btn.Click
    connectionString = "Data Source=MININT-BJDM4MI;AttachDbFilename=C:\Program Files\Microsoft SQL Server\MSSQL12.MSSQLSERVER\MSSQL\DATA\QCDB.mdf;Database=QCDB;Trusted_Connection=Yes;"
    sql = "SELECT * FROM PRODUCT WHERE SAMPLE_SOURCE = @SOURCE"

    Dim connection As New SqlConnection(connectionString)
    Dim dataadapter As New SqlDataAdapter(sql, connection)
    Dim ds As New System.Data.DataSet()
    Dim cmd = New SqlCommand(sql, connection)

    cmd.Parameters.AddWithValue("@SOURCE", spl_source_combox.Text)

    Try
        connection.Open()
        dataadapter.Fill(ds, "PRODUCT")
        DataGridView1.Refresh()
        cmd.ExecuteNonQuery()
        connection.Close()
        DataGridView1.DataSource = ds.Tables(0)
    Catch ex As Exception
        MessageBox.Show(ex.ToString)
    End Try
End Sub

Answer 1

如果您使用存储过程而不是在代码中传递sql会更好，但是您的异常的原因是因为@SOURCE变量未在您的SQL语句中声明。试试这个：

UIAlertViewController

Answer 2

创建SqlDataAdapter时，应该传入命令对象而不是SQL字符串。

Private Sub search_btn_Click(sender As Object, e As EventArgs) Handles search_btn.Click
connectionString = "Data Source=MININT-BJDM4MI;AttachDbFilename=C:\Program Files\Microsoft SQL Server\MSSQL12.MSSQLSERVER\MSSQL\DATA\QCDB.mdf;Database=QCDB;Trusted_Connection=Yes;"
sql = "SELECT * FROM PRODUCT WHERE SAMPLE_SOURCE = @SOURCE"

Dim connection As New SqlConnection(connectionString)
Dim cmd = New SqlCommand(sql, connection)
Dim dataadapter As New SqlDataAdapter(cmd)
Dim ds As New System.Data.DataSet()

cmd.Parameters.AddWithValue("@SOURCE", spl_source_combox.Text)

Try
    connection.Open()
    dataadapter.Fill(ds, "PRODUCT")
    DataGridView1.Refresh()
    connection.Close()
    DataGridView1.DataSource = ds.Tables(0)
Catch ex As Exception
    MessageBox.Show(ex.ToString)
End Try
End Sub

Answer 3

您需要为@source分配值：使用此行

cmd.Parameters.AddWithValue("@SOURCE", spl_source_combox.Text) = "<Your Value>"

必须声明标量变量（SQL）

3 个答案: