Question

以下代码假设创建一个数据库和一个带有“FirstName”列的表，该列被赋值为“James”

Imports System.Data.SQLite
Public Class Form1
    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        SQLiteConnection.CreateFile("c:\mydatabasefile.db3")
        Dim sqlConnection As New SQLite.SQLiteConnection()
        Dim sqlCommand As New SQLiteCommand

        sqlConnection.ConnectionString = "Data Source=c:\mydatabasefile.db3"
        sqlConnection.Open()
        sqlCommand.CommandText = "CREATE TABLE MyTable(EmpID INTEGER PRIMARY KEY ASC,  FirstName VARCHAR(25));"
        sqlCommand.CommandText = "INSERT INTO MyTable(FirstName) VALUES('James');"
        sqlConnection.Close()
    End Sub
End Class

但由于某种原因，应用程序只创建一个大小为0字节的数据库。为什么不起作用。我正在使用我正在使用SQLite ADO.NET Provider。，VS 2010，Winforms

Answer 1

您永远不会执行sql命令

Public Class Form1
    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        SQLiteConnection.CreateFile("c:\mydatabasefile.db3")
        Dim sqlConnection As New SQLite.SQLiteConnection()
        Dim sqlCommand As New SQLiteCommand("", sqlConnection)

        sqlConnection.ConnectionString = "Data Source=c:\mydatabasefile.db3"
        sqlConnection.Open()
        sqlCommand.CommandText = "CREATE TABLE MyTable(EmpID INTEGER PRIMARY KEY ASC,  FirstName VARCHAR(25));"
        sqlCommand.ExecuteNonQuery()
        sqlCommand.CommandText = "INSERT INTO MyTable(FirstName) VALUES('James');"
        sqlCommand.ExecuteNonQuery()
        sqlConnection.Close()
    End Sub


End Class

您还需要设置命令连接，您也可以通过

来设置

sqlCommand.Connection = sqlConnection 这应该会解决你的问题

Answer 2

您永远不会执行sqlCommands。你应该使用.ExecuteNonQuery（）来获取数据库中的内容，否则什么都不会做。

Answer 3

还要让命令知道要使用的连接。 sqlCommand.Connection = sqlConnection

无法创建表格和在数据库中插入值

3 个答案: