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vb.net - 未创建 SQLite 数据库创建

问题描述

我将我的 SQLite 数据库名称存储在 App.config 中并使用 System.Configuration Reference 来检索数据库名称
我认为这没有任何价值，所以我删除了 readConfig 代码
现在我无法创建数据库及其两个表
有人会好心吗足以查看下面的代码并解释我做错了什么？

模块中的设置

Public gv_dbName As String = "Notes.db"

frmStart 上的顶级声明

Public connStr As String = "Data Source={0};Version=3;"
Public conn As SqliteConnection
Dim cmd As SqliteCommand

其他相关代码

    Private Sub frmStart_Load(sender As Object, e As EventArgs) Handles MyBase.Load

    Icon = Icon.ExtractAssociatedIcon(Application.ExecutablePath)
    connStr = String.Format(connStr, gv_dbName)

    If My.Computer.FileSystem.FileExists(gv_dbName) Then
        btnCreate.Visible = False
        btnToEnterData.Visible = True
        btnToViewParentTable.Visible = True
    ElseIf Not My.Computer.FileSystem.FileExists(gv_dbName) Then
        conn = New SqliteConnection($"Data Source = '{gv_dbName}';Version=3;")
        tbMessage.Text = "Created Database & Tables"
    End If

End Sub

Private Sub btnCreate_Click(sender As Object, e As EventArgs) Handles btnCreate.Click
    makeDB()
End Sub

Public Sub makeDB()

    If Not My.Computer.FileSystem.FileExists(gv_dbName) Then
        Try
            conn = New SqliteConnection($"Data Source = '{gv_dbName}';Version=3;")
            conn.Open()
            makeParentTable()
            makeChildTable()
            conn.Close()
        Catch ex As Exception
            tbMessage.Text = "Database NOT Created"
        End Try
    End If

End Sub

我什至尝试过这个顶级的 frmStart

'Friend gv_dbName As String = "Notes.db"

这是我基于
链接到代码的代码

标签： vb.netsqlite

解决方案

使用Microsoft.Data.Sqlite.Coreor System.Data.SQLite (Db Version 3)查看文件是否存在并不重要。只需给出一个物理/绝对路径，如果不存在则创建一个新文件named.db，否则返回现有数据库：

例子：

Friend dbPath As String = IO.Path.Combine(Application.StartupPath, "Notes.db")

Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
    TestMySqlite()
End Sub


Private Sub TestMySqlite()
    Try

        'You can use this but it is not important for version 3 as is auto created the new file by itself
        'If Not IO.File.Exists(dbPath) Then SQLiteConnection.CreateFile(dbPath)

        Using conn As SQLiteConnection = New SQLiteConnection("Data Source=" & dbPath & "; Version=3;")

            conn.Open()
            Console.WriteLine(conn.FileName)

            Using command As SQLiteCommand = New SQLiteCommand("CREATE TABLE IF NOT EXISTS  Test (RowIndex INTEGER PRIMARY KEY AUTOINCREMENT COLLATE NOCASE, name varchar(20))", conn)
                command.ExecuteNonQuery()
            End Using

            Using cmdInsert = New SQLiteCommand("INSERT INTO Test (name) values ('this is a test')", conn)
                cmdInsert.ExecuteNonQuery()
            End Using

        End Using

    Catch ex As Exception
        Console.WriteLine(ex.ToString)
        Stop
    End Try

End Sub

在此示例中，在您的应用程序运行的文件夹下创建了一个名为 Notes.db 的文件（如果不存在）。下一次调用 SQLiteConnection 只返回 Notes.db

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