ExecuteReader: CommandText 属性尚未初始化
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
using System.Data.SqlClient;

namespace Student
{
public partial class RPT : Form
{
public RPT()
{
InitializeComponent();
}
private string Rptstrconn;
private SqlConnection sqlrptconn;
private SqlDataAdapter sqlrptda;
private string Rptconnstr="Data Source=WWW-F9EEA54BDCA;Initial Catalog=STUDENT;User ID=sa;Pwd=jxlsqd;Integrated Security=False";
private SqlCommandBuilder sqlrptcomm;
private DataSet Rptset = new DataSet();

private void button1_Click(object sender, EventArgs e)
{
Rptstrconn = "select * from REWARD_PUNUSHMENT where STUDENT = " + "'" + txtrpt.Text.ToString().Trim() + "'";
sqlrptconn = new SqlConnection(this.Rptconnstr);
sqlrptda = new SqlDataAdapter(this.Rptstrconn, this.sqlrptconn);
Rptset.Clear();

sqlrptda.Fill(Rptset, "REWARD_PUNUSHMENT");
datrpt.DataSource = Rptset.Tables[0];
}

private void button5_Click(object sender, EventArgs e)
{
int row = this.datrpt.VisibleRowCount;
this.datrpt.CurrentCell = new DataGridCell(row + 1, 0);
}

private void RPT_Load(object sender, EventArgs e)
{
Rptstrconn = "select ID as 记录号,STUDENT as 学号,LEVEL as 奖惩代号,TIME as 奖惩时间,DESCRIPTION as 描述 from REWARD_PUNUSHMENT";
sqlrptconn = new SqlConnection(this.Rptconnstr);
sqlrptda = new SqlDataAdapter(this.Rptstrconn, this.sqlrptconn);
Rptset.Clear();

sqlrptda.Fill(Rptset, "REWARD_PUNUSHMENT");
datrpt.DataSource = Rptset.Tables[0];
}

private void button4_Click(object sender, EventArgs e)
{
if (MessageBox.Show("您确定要退出系统吗？", "确认", MessageBoxButtons.OKCancel) == DialogResult.OK)
this.Close();
}

private void button2_Click(object sender, EventArgs e)
{
int row = this.datrpt.VisibleRowCount;
this.datrpt.CurrentCell = new DataGridCell(row + 1, 0);
if (Rptset.HasChanges())
{
sqlrptconn = new SqlConnection(this.Rptconnstr);
sqlrptda = new SqlDataAdapter(this.Rptstrconn, this.sqlrptconn);
sqlrptcomm = new SqlCommandBuilder(sqlrptda);
sqlrptda.Update(Rptset.GetChanges(), "REWARD_PUNUSHMENT");
Rptset.AcceptChanges();
MessageBox.Show("信息修改成功！");
}
}

private void button3_Click(object sender, EventArgs e)
{
int rowNumber = this.datrpt.CurrentCell.RowNumber;
//try
//{
this.Rptset.Tables[0].Rows[rowNumber].Delete();
// DataSet Rptset = new DataSet();
this.sqlrptconn = new SqlConnection(this.Rptconnstr);
sqlrptda = new SqlDataAdapter("", sqlrptconn);
sqlrptcomm = new SqlCommandBuilder(sqlrptda);

sqlrptda.Update(this.Rptset.GetChanges(), "REWARD_PUNUSHMENT"); MessageBox.Show("信息删除成功！");
//}
//catch
//{ MessageBox .Show ("更新失败！");}
}
}
}

sqlrptda.Update(this.Rptset.GetChanges(), "REWARD_PUNUSHMENT"); 每次都报错 ExecuteReader: CommandText 属性尚未初始化 各位帮我看哈啊 在线等了！！！！！！！！！！

[解决办法]
问题出在你的定义上面。这样的定义每次都要初始化一遍，不管你怎么赋值。一个解决方案是加static关键字。
private static string Rptstrconn;
private static SqlConnection sqlrptconn;
private static SqlDataAdapter sqlrptda;
private static string Rptconnstr="Data Source=WWW-F9EEA54BDCA;Initial Catalog=STUDENT;User ID=sa;Pwd=jxlsqd;Integrated Security=False";
private static SqlCommandBuilder sqlrptcomm;
private static DataSet Rptset = new DataSet();

另外一个解决方案是用ViewStat。
[解决办法]
private void button3_Click(object sender, EventArgs e)
{
int rowNumber = this.datrpt.CurrentCell.RowNumber;
this.Rptset.Tables[0].Rows[rowNumber].Delete();
this.sqlrptconn = new SqlConnection(this.Rptconnstr);
sqlrptda = new SqlDataAdapter("", sqlrptconn);//你的查询语句跑那里去了?
sqlrptcomm = new SqlCommandBuilder(sqlrptda);
sqlrptda.Update(this.Rptset.GetChanges(), "REWARD_PUNUSHMENT");
MessageBox.Show("信息删除成功！");
}
[解决办法]
你执行的sql语句是空的当然提示没有初始化了。
[解决办法]
不指定查询语句，适配器不知道要更新的是哪张表