想做个数据库查询工具，通过下拉菜单选定数据库（多个库），该怎么做这个单选菜单呢？

Question

2005里好像没有直接的属性。要选中一个其他选项解除选定的效果。

Answer 1

You can use state management design pattern to do this. Here is my example.
public partial class MainForm : Form
{
    private readonly MenuCheckStateManager manager;    public MainForm()
    {
        InitializeComponent();        ToolStripMenuItem redMenu = new ToolStripMenuItem("Red", null, OnMenuClick);
        ToolStripMenuItem greenMenu = new ToolStripMenuItem("Green", null, OnMenuClick);
        ToolStripMenuItem blueMenu = new ToolStripMenuItem("Blue", null, OnMenuClick);        ToolStripMenuItem colorMenu = new ToolStripMenuItem("Colors", null, redMenu, greenMenu, blueMenu);        MenuStrip menuBar = new MenuStrip();
        menuBar.Items.Add(colorMenu);        this.Controls.Add(menuBar);        this.manager = new MenuCheckStateManager(new ToolStripMenuItem[] { redMenu, greenMenu, blueMenu });
    }    protected override void DestroyHandle()
    {
        base.DestroyHandle();        this.manager.Dispose();
    }    private void OnMenuClick(object sender, EventArgs e)
    {
        ToolStripMenuItem menu = (ToolStripMenuItem)sender;
        this.manager.Change(menu);
    }
}public class MenuCheckStateManager : IDisposable
{
    private IEnumerable<ToolStripMenuItem> menus;    public MenuCheckStateManager(IEnumerable<ToolStripMenuItem> menus)
    {
        if (menus == null) throw new ArgumentNullException("menus");        this.menus = menus;
    }    public void Change(ToolStripMenuItem menuToCheck)
    {
        if (menuToCheck == null) throw new ArgumentNullException("menuToCheck");        foreach (var menu in this.menus.Where(m => !m.Equals(menuToCheck)))
        {
            menu.Checked = false;
        }        menuToCheck.Checked = true;
    }    public void Dispose()
    {
        Dispose(true);
        GC.SuppressFinalize(this);
    }
    protected virtual void Dispose(bool disposing)
    {
        if (disposing)
        {
            lock (this)
            {
                this.menus = null;
            }
        }
    }
    ~MenuCheckStateManager()
    {
        Dispose(false);
    }
}

Answer 2

库的话 貌似不行，因为你正常连数据库的话需要一个库名的，如果非要读的话 可以读读 tnsnames.ora
但可以读出某个库的所有表名，每个表的所有列名
/// <summary>
        /// 查询指定数据库中的所有表，oracle、sqlserver、mysql
        /// </summary>
        /// <param name="databasetype"></param>
        /// <returns></returns>
        public ArrayList queryTables(string databasetype)
        {
            ArrayList list = new ArrayList();
            if (databasetype.Equals("Oracle"))
            {
                try
                {
                    string str = "SELECT * FROM user_all_tables order by table_name asc";
                    OracleDataAdapter da = new OracleDataAdapter(str, oracleconn);
                    DataSet ds = new DataSet();
                    da.Fill(ds);
                    DataTable dt = ds.Tables[0];
                    foreach (DataRow dr in dt.Rows)
                    {
                        list.Add(dr[0].ToString().Trim());
                    }
                    flag = true;
                    return list;
                }
                catch (OracleException ee)
                {
                    MessageBox.Show(ee.Message.ToString());
                    flag = false;
                    return null;
                }
            }
            else if (databasetype.Equals("SQLServer"))
            {
                try
                {
                    string str = "SELECT * FROM sys.tables";
                    SqlDataAdapter da = new SqlDataAdapter(str, sqlserverconn);
                    DataSet ds = new DataSet();
                    da.Fill(ds);
                    DataTable dt = ds.Tables[0];
                    foreach (DataRow dr in dt.Rows)
                    {
                        list.Add(dr[0].ToString().Trim());
                    }
                    flag = true;
                    return list;
                }
                catch (SqlException ee)
                {
                    MessageBox.Show(ee.Message.ToString());
                    flag = false;
                    return null;
                }
            }
            else
            {
                try
                {
                    string str = "show tables";
                    MySQLDataAdapter da = new MySQLDataAdapter(str, mysqlconn);
                    DataSet ds = new DataSet();
                    da.Fill(ds);
                    DataTable dt = ds.Tables[0];
                    foreach (DataRow dr in dt.Rows)
                    {
                        list.Add(dr[0].ToString().Trim());
                    }
                    flag = true;
                    return list;
                }
                catch (MySQLException ee)
                {
                    MessageBox.Show(ee.Message.ToString());
                    flag = false;
                    return null;
                }
            }        }

Answer 3

I added comments in the source code. Because I don't know your technical level, I guess you might need these comments. I also changed LINQ codes into comparison statements.
public partial class MainForm : Form
{
    private readonly MenuCheckStateManager manager;    public MainForm()
    {
        InitializeComponent();        // Create menus
        ToolStripMenuItem redMenu = new ToolStripMenuItem("Red", null, OnMenuClick);
        ToolStripMenuItem greenMenu = new ToolStripMenuItem("Green", null, OnMenuClick);
        ToolStripMenuItem blueMenu = new ToolStripMenuItem("Blue", null, OnMenuClick);        ToolStripMenuItem colorMenu = new ToolStripMenuItem("Colors", null, redMenu, greenMenu, blueMenu);        MenuStrip menuBar = new MenuStrip();
        menuBar.Items.Add(colorMenu);        this.Controls.Add(menuBar);        // Register checkable menus with MenuCheckStateManager
        this.manager = new MenuCheckStateManager(new ToolStripMenuItem[] { redMenu, greenMenu, blueMenu });
    }    protected override void DestroyHandle()
    {
        base.DestroyHandle();        // Clear the hold menus, so the menus can be garbage collected
        this.manager.Dispose();
    }    private void OnMenuClick(object sender, EventArgs e)
    {
        // change menu check state on click
        ToolStripMenuItem menu = (ToolStripMenuItem)sender;
        this.manager.Change(menu);
    }
}// Check state manager
public class MenuCheckStateManager : IDisposable
{
    private IEnumerable<ToolStripMenuItem> menus;    public MenuCheckStateManager(IEnumerable<ToolStripMenuItem> menus)
    {
        if (menus == null) throw new ArgumentNullException("menus");        this.menus = menus;
    }    public void Change(ToolStripMenuItem menuToCheck)
    {
        if (menuToCheck == null) throw new ArgumentNullException("menuToCheck");        foreach (ToolStripMenuItem menu in this.menus)
        {
            menu.Checked = menu == menuToCheck;
        }
    }    // Implement IDisposable interface.
    // You can google on the Internet for more information about how to implement IDisposable interface.
    public void Dispose()
    {
        Dispose(true);
        GC.SuppressFinalize(this);
    }
    protected virtual void Dispose(bool disposing)
    {
        if (disposing)
        {
            lock (this)
            {
                this.menus = null;
            }
        }
    }
    ~MenuCheckStateManager()
    {
        Dispose(false);
    }
}

Answer 4

请参考这个http://www.6down.net/soft/html/3317.html 个人觉的这个这个比较好.