使用 VB.NET 表单从 SQL Server 到 Excel 的日期明智的数据检索

Question

我想创建一个报告软件，在该软件中，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打开连接。 连接是宝贵的资源。 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，您将看到一个.Dispose方法。 当你看到它时，这意味着应该调用它来释放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。 简而言之，不要将工作簿变暗为对象，范围不是Excel.Application的成员，并始终Excel.Application 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