在Datatable，DataView和DataGridView中不显示重复的记录
其中，对于直接在查询语句中使用distinct不作过多说明，主要从代码层角度实现
方法一，在加载数据的时候，对于重复的数据，选择不进行加载。
代码如下：
OleDbConnection conn = new OleDbConnection(@"Provider=Microsoft.ACE.OLEDB.12.0;Data Source=C:\Program\Database\employInfo.accdb"); conn.Open(); OleDbDataReader dr; OleDbCommand view = new OleDbCommand("SELECT * FROM Employ", conn); dataGridView1.Rows.Clear(); dr = view.ExecuteReader(); int ii = dataGridView1.Rows.Count; bool isexist = false; while (dr.Read()) { if (dataGridView1.Rows.Count == 0) { dataGridView1.Rows.Add(dr["EmployId"], dr["EmployName"], dr["EmployCompany"]); } else { for (int i = 0; i < dataGridView1.Rows.Count; i++) { if (dataGridView1.Rows[i].Cells["EmployId"].Value.ToString() == dr["EmployId"].ToString() && dataGridView1.Rows[i].Cells["EmployName"].Value.ToString() == dr["EmployName"].ToString() && dataGridView1.Rows[i].Cells["EmployCompany"].Value.ToString() == dr["EmployCompany"].ToString()) { isexist=true; break; } } if (!isexist) { dataGridView1.Rows.Add(dr["EmployId"], dr["EmployName"], dr["EmployCompany"]); } isexist = false; } } dr.Close(); conn.Close();方法二.在现有的Datatable中去重，.net2.0提供了一个非常有效的方法DataView.ToTable 方法
具体代码如下：
OleDbConnection conn = new OleDbConnection(@"Provider=Microsoft.ACE.OLEDB.12.0;Data Source=C:\Program\Database\employInfo.accdb"); conn.Open(); OleDbDataReader dr; OleDbCommand view = new OleDbCommand("SELECT * FROM Employ", conn); dataGridView1.Rows.Clear(); dr = view.ExecuteReader(); int ii = dataGridView1.Rows.Count; bool isexist = false; while (dr.Read()) { dataGridView1.Rows.Add(dr["EmployId"], dr["EmployName"], dr["EmployCompany"]); } dr.Close(); conn.Close(); DataTable dt = new DataTable(); OleDbDataAdapter da = new OleDbDataAdapter(); da.SelectCommand = view; da.Fill(dt); DataTable dtnew = dt.DefaultView.ToTable(true); dataGridView2.DataSource = dtnew;//dtnew and dt both are DataTable 关于DataView.ToTable 方法可以参照如下链接：
http://msdn.microsoft.com/zh-cn/library/wec2b2e6(v=vs.110).aspx