Question

我使用OleDbConnection连接到带有WPF的C＃Visual Studio 2013的MS Access 2013数据库，并且我在我的连接类中使用了外观设计模式 -

public class Connection
{
    private readonly OleDbConnection con;
    private readonly string path;
    private bool connected;

    public Connection(string path)
    {
        connected = false;
        this.path = path;
        string conString = @"Provider=Microsoft.ACE.OLEDB.12.0; Data Source=" + path + ";";
        this.con = new OleDbConnection(conString);
    }

    public string Path { get { return path; } }
    public bool Connected { get { return connected; } }

    public void Open()
    {
        this.con.Open();
        connected = true;
    }

    public DataSet GetData(string sql) // get dataset of with data of this sql query
    {
        OleDbDataAdapter adapter = new OleDbDataAdapter(sql, con);
        DataSet ds = new DataSet();
        adapter.Fill(ds);
        return ds;
    }

    public T GetItem<T>(string sql) // get an single item
    {
        return (T) GetData(sql).Tables[0].Rows[0][0];
    }

    public void Execute(string sql) // execute Insert, Delete etc..
    {
        OleDbCommand ocmd = new OleDbCommand();
        ocmd.CommandText = sql;
        ocmd.Connection = con;
        Execute(ocmd);  

    }

    public void Execute(OleDbCommand cmd)
    {
        cmd.ExecuteNonQuery();
        cmd.Dispose();
    }

    public void Close()
    {
        this.con.Close();
        connected = false;
    }

    public override string ToString()
    {
        return "[Connection: Path=" + path + "Connected=" + connected + " ]";
    }

}

GetData方法有效。 Execute方法似乎有效，但是当我查看数据库时它并没有改变任何东西，那么奇怪的是：

Connection db = new Connection("Database\\Database.accdb");
db.Open();
int count = db.GetItem<int>("SELECT COUNT(ScoreID) FROM tblScores");
Console.WriteLine(count); // prints 1
db.Execute("INSERT INTO tblScores VALUES (1, 'My Awsome Name', 'Easy', 3, Date())");
count = db.GetItem<int>("SELECT COUNT(ScoreID) FROM tblScores");
Console.WriteLine(count); // prints 2 (??)
db.Close();

运行后我查看数据库，但我看不到这行... 我尝试直接在访问时运行查询（打开MS Access 2013）并且它工作正常。当我尝试使用已经在其中的主键执行查询时抛出异常，那么这里有什么问题？

Answer 1

public void Execute(string sql) // execute Insert, Delete etc..
{
    OleDbCommand ocmd = new OleDbCommand();
    ocmd.CommandText = sql;
    ocmd.Connection = con;
    Execute(ocmd);  

}

public void Execute(OleDbCommand cmd)
{
    try
    {
        int result = cmd.ExecuteNonQuery();
        cmd.Dispose();
    }
    catch (Exception ex)
    {
        Console.Write(ex.Message);
    }
}

问题可能出在你的INSERT语句中 - 在Access数据库中，Date必须用＃符号包裹起来：

"INSERT INTO tblScores VALUES (1, 'My Awsome Name', 'Easy', 3, #" + DateTime.Now() + "#)"

C＃ - ExecuteNonQuery

1 个答案: