MySql.Data.MySqlClient.MySqlException：'重复字段'

Question

当我尝试将数据插入数据库时​​，它显示为

  

'MySql.Data.MySqlClient.MySqlException：重复字段'

即使它不是主键。我也使用代码检查datagridview中的重复项。

If DataGridView1.RowCount = 0 Then
    Dim x As DialogResult
    x = MessageBox.Show("Enter the Values", "TDP Thermoline",
                        MessageBoxButtons.OK, MessageBoxIcon.Exclamation)
Else
    Dim bolDuplicateWasFound As Boolean = False
    For x As Integer = 0 To DataGridView1.Rows.Count - 1
        For y As Integer = 0 To DataGridView1.Rows.Count - 1
            If y <> x AndAlso DataGridView1.Rows(x).Cells("Date").Value = DataGridView1.Rows(y).Cells("Date").Value.ToString Then
                MessageBox.Show("Duplicate Found" & DataGridView1.Rows(x).Cells("Date").Value.ToString)
                Exit Sub
            End If
        Next
    Next
    If Not bolDuplicateWasFound Then
        Dim command As MySqlCommand
        For i As Integer = 0 To DataGridView1.Rows.Count - 1 Step +1
            command = New MySqlCommand("INSERT INTO `daily_production`(`Year`, `Month`, `Date`, `White`, `Yellow`) 
            VALUES (@yea,@mon,@dat,@whit,@yel)", db.getConnection)
            command.Parameters.Add("@yea", MySqlDbType.VarChar).Value = DataGridView1.Rows(i).Cells(0).Value.ToString
            command.Parameters.Add("@mon", MySqlDbType.VarChar).Value = DataGridView1.Rows(i).Cells(1).Value.ToString
            command.Parameters.Add("@dat", MySqlDbType.VarChar).Value = DataGridView1.Rows(i).Cells(2).Value.ToString
            command.Parameters.Add("@whit", MySqlDbType.VarChar).Value = DataGridView1.Rows(i).Cells(3).Value.ToString
            command.Parameters.Add("@yel", MySqlDbType.VarChar).Value = DataGridView1.Rows(i).Cells(4).Value.ToString
            db.getConnection.Open()
            command.ExecuteNonQuery()
        Next
        MessageBox.Show("Data Insert", "TDP Thermoline", MessageBoxButtons.OK, MessageBoxIcon.Information)
        db.getConnection.Close()
        db.getConnection.Dispose()
    End If
End If

如何清除该错误？