访问数据库文件中的数据

本文关键字：数据 文件 数据库 访问 | 更新日期: 2023-09-27 18:00:47

我不确定，但我无法获得要在文本框中显示的数据。这是我迄今为止写的代码。任何帮助都会很棒。盒子里什么都没有，但在做测试时，我收到了消息框。有什么地方我做得不对吗？如果需要，我可以提供访问文件。但它只有五个字段有数据

DataSet DataSet1; //use to put data in form
System.Data.OleDb.OleDbDataAdapter dataadapter;
private void Breed_Load(object sender, EventArgs e)
{
    dbconnect = new System.Data.OleDb.OleDbConnection();//database connection variable
    DataSet1 = new DataSet(); //variable to help get info from DB
    dbconnect.ConnectionString = "PROVIDER= Microsoft.Jet.OLEDB.4.0; Data Source=C:/Pets.mdb"; //location of DB to open
    dbconnect.Open(); //open command for DB
    string sql = "SELECT * From tblPets"; //sql string to select all records from the table pets
    dataadapter = new System.Data.OleDb.OleDbDataAdapter(sql, dbconnect); // pulls the records from sql command
    MessageBox.Show("Database is Open");
    dataadapter.Fill(DataSet1, "Pets"); // used the database to fill in the form.
    NavRecords(); //calls NavRecords Method
    dbconnect.Close();
   MessageBox.Show("Database is Closed");
    dbconnect.Dispose(); 

}

private void NavRecords()
{
    DataRow DBrow = DataSet1.Tables["Pets"].Rows[0];
    //PetNametextBox.Text = DBrow.ItemArray.GetValue(1).ToString(); //puts data in textbox
    TypeofPettextBox.Text = DBrow.ItemArray.GetValue(1).ToString();//puts data in textbox
    PetWeighttextBox.Text = DBrow.ItemArray.GetValue(2).ToString();//puts data in textbox
    ShotsUpdatedtextBox.Text = DBrow.ItemArray.GetValue(3).ToString();//puts data in textbox
    AdoptabletextBox.Text = DBrow.ItemArray.GetValue(4).ToString();//puts data in textbox
    BreedtextBox.Text = DBrow.ItemArray.GetValue(5).ToString();//puts data in textbox
}

访问数据库文件中的数据

从Access数据库中获取数据相当简单。这里有一个例子：

public static DataTable GetBySQLStatement(string SQLText)
{
    System.Data.OleDb.OleDbCommand cmd = new System.Data.OleDb.OleDbCommand();
    string ConnectionString = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=C:''Pets.MDB";
    System.Data.OleDb.OleDbConnection Conn = new System.Data.OleDb.OleDbConnection();
    Conn.ConnectionString = ConnectionString;
    cmd.CommandType = CommandType.Text;
    cmd.Connection = Conn;
    cmd.CommandText = SQLText;
    DataSet ds;
    System.Data.OleDb.OleDbDataAdapter da;
    DataTable Table = null;
    Conn.Open();
    da = new System.Data.OleDb.OleDbDataAdapter();
    da.SelectCommand = cmd;
    ds = new DataSet();
    da.Fill(ds);
    if (ds.Tables.Count > 0)
        Table = ds.Tables[0];
    Conn.Close();
    return Table;
}

你这样调用这个函数：

DataTable dt = GetBySQLStatement("SELECT * FROM tblPets");
if (dt != null) {
    // If all goes well, execution should get to this line and
    // You can pull your data from dt, like dt[0][0]
}

唯一需要注意的是，由于没有64位Jet驱动程序，因此必须将此代码编译为32位应用程序。默认情况下，Visual Studio将作为32位和64位的混合程序进行编译。更改项目设置中的选项以确保其仅为32位。

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