使用 VB.NET 表单从 SQL Server 到 Excel 的日期数据检索

Question

我想创建一个报告软件，在其中通过用户表单中的 datepicker 工具在用户指定的日期检索日期。我想知道如何实现代码以获得结果。

这是我的代码...请帮助我。我是新手

Imports System.Data
Imports System.Data.SqlClient

Public Class Form1
    Private conn As New SqlConnection
    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load

        Try
            conn.ConnectionString = "Data Source=ROG\SQLEXPRESS;Initial Catalog=GKEAPL;Integrated Security=True;"
            conn.Open()
            MsgBox("Connected")
        Catch ex As Exception
            MsgBox("Could Not connect")
        End Try
    End Sub

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click

        Try
            Dim officeexcel As New Microsoft.Office.Interop.Excel.Application
            officeexcel = CreateObject("Excel.Application")
            Dim workbook As Object = officeexcel.Workbooks.Add("D:\GKEAPL\project 1\gk format.xltx")
            officeexcel.Visible = True
            Dim da As New SqlDataAdapter
            Dim ds As New DataSet
            da = New SqlDataAdapter("SELECT FeedWaterTankLevelFWST101,
                                    FeedFlowFT101,
                                    ClearWaterTankLevelCWST201,
                                    TMFilPressurePT201,
                                    TMFolPressurePT202,
                                    HPPilPressurePT203,
                                    MembraneilPressurePT204,
                                    MembraneolPressurePT205,
                                    PermeateFlowFT201,
                                    RejectFlowFT202
                 FROM DATA1 WHERE(DATEnTIME >='2020-12-18 11:06:30.000' AND DATEnTIME <= '2020-12-19 10:07:31.000')", conn)
            da.Fill(ds, "DATA1")

            For i As Integer = 0 To ds.Tables("DATA1").Rows.Count - 1

                With officeexcel
                    .Range("Sheet2!B" + (i + 7).ToString).Value = ds.Tables("DATA1").Rows(i).Item(0).ToString
                    .Range("Sheet2!C" + (i + 7).ToString).Value = ds.Tables("DATA1").Rows(i).Item(1).ToString
                    .Range("Sheet2!D" + (i + 7).ToString).Value = ds.Tables("DATA1").Rows(i).Item(2).ToString
                    .Range("Sheet2!E" + (i + 7).ToString).Value = ds.Tables("DATA1").Rows(i).Item(3).ToString
                    .Range("Sheet1!F" + (i + 7).ToString).Value = ds.Tables("DATA1").Rows(i).Item(4).ToString
                    .Range("Sheet1!G" + (i + 7).ToString).Value = ds.Tables("DATA1").Rows(i).Item(5).ToString
                    .Range("Sheet1!H" + (i + 7).ToString).Value = ds.Tables("DATA1").Rows(i).Item(6).ToString
                    .Range("Sheet1!I" + (i + 7).ToString).Value = ds.Tables("DATA1").Rows(i).Item(7).ToString
                    .Range("Sheet1!J" + (i + 7).ToString).Value = ds.Tables("DATA1").Rows(i).Item(8).ToString
                    .Range("Sheet1!K" + (i + 7).ToString).Value = ds.Tables("DATA1").Rows(i).Item(9).ToString
                End With
            Next

            officeexcel = Nothing
            workbook = Nothing
        Catch ex As Exception

        End Try

    End Sub
    Private Sub Report_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        DateTimePicker1.CustomFormat = "YYYY-MMMM-DD"
    End Sub

End Class

Answer 1

不要在Form.Load 中打开连接。人脉是宝贵的资源。将它们保留在使用它们的方法的本地。在.Execute... 行之前打开并尽快关闭。

如果您查看 MS 文档 https://docs.microsoft.com/en-us/dotnet/api/system.data.sqlclient.sqlconnection?view=dotnet-plat-ext-3.1 中的 SQLConnection 类，您将看到 .Dispose 方法。当您看到它时，这意味着应该调用它来释放该类使用的非托管资源。幸运的是，vb.net 提供了Using...End Using 块来为我们处理这个问题。

我将您的数据访问代码移到了单独的函数中。一个方法应该尽可能只做一件事。

在您的 sql 字符串 WHERE 子句中，我将您的文字更改为参数并使用了 BETWEEN。

我认为您的 Excel 代码也有问题，但您的问题是关于数据访问的。简而言之，不要将工作簿作为对象进行调暗，Range 不是Excel.Application 的成员，并且现在并始终打开 Option Strict。

Private Function GetTankData() As DataTable
    Dim dt As New DataTable
    Dim strSql = "SELECT FeedWaterTankLevelFWST101,
                                FeedFlowFT101,
                                ClearWaterTankLevelCWST201,
                                TMFilPressurePT201,
                                TMFolPressurePT202,
                                HPPilPressurePT203,
                                MembraneilPressurePT204,
                                MembraneolPressurePT205,
                                PermeateFlowFT201,
                                RejectFlowFT202
             FROM DATA1 WHERE DATEnTIME BETWEEN @StartDate AND  @EndDate"
    Using conn As New SqlConnection("Data Source=ROG\SQLEXPRESS;Initial Catalog=GKEAPL;Integrated Security=True;"),
            cmd As New SqlCommand(strSql, conn)
        cmd.Parameters.Add("@StartDate", SqlDbType.DateTime).Value = DateTimePicker1.Value
        cmd.Parameters.Add("@EndDate", SqlDbType.DateTime).Value = DateTimePicker2.Value
        conn.Open()
        dt.Load(cmd.ExecuteReader)
    End Using 'Closes and disposes the connection and command
    Return dt
End Function

Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
    Dim officeexcel As New Microsoft.Office.Interop.Excel.Application
    officeexcel = CreateObject("Excel.Application")
    Dim workbook As Object = officeexcel.Workbooks.Add("D:\GKEAPL\project 1\gk format.xltx")
    Try
        officeexcel.Visible = True
        Dim dt = GetTankData()

        For i As Integer = 0 To dt.Rows.Count - 1

            With officeexcel
                .Range("Sheet2!B" + (i + 7).ToString).Value = dt.Rows(i).Item(0).ToString
                .Range("Sheet2!C" + (i + 7).ToString).Value = dt.Rows(i).Item(1).ToString
                .Range("Sheet2!D" + (i + 7).ToString).Value = dt.Rows(i).Item(2).ToString
                .Range("Sheet2!E" + (i + 7).ToString).Value = dt.Rows(i).Item(3).ToString
                .Range("Sheet1!F" + (i + 7).ToString).Value = dt.Rows(i).Item(4).ToString
                .Range("Sheet1!G" + (i + 7).ToString).Value = dt.Rows(i).Item(5).ToString
                .Range("Sheet1!H" + (i + 7).ToString).Value = dt.Rows(i).Item(6).ToString
                .Range("Sheet1!I" + (i + 7).ToString).Value = dt.Rows(i).Item(7).ToString
                .Range("Sheet1!J" + (i + 7).ToString).Value = dt.Rows(i).Item(8).ToString
                .Range("Sheet1!K" + (i + 7).ToString).Value = dt.Rows(i).Item(9).ToString
            End With
        Next
    Finally
        officeexcel = Nothing
        workbook = Nothing

    End Try

End Sub