IndexOutOfRangeException这个异常

[枫叶丿飘]

/// <summary>
/// 得到该节点下的最大值Id
/// </summary>
/// <param name="linkid"></param>
/// <returns></returns>
public Test GetMaxId(int linkid)
{
try
{
String sql = "select max(Id) from test3 where linkid=@linkid" ;
SqlDataReader sdr = DBHelper.GetReader(sql,new SqlParameter("@linkid",linkid));
if (sdr.Read())
{
Test test = new Test();

test.Id = Convert.ToInt32(sdr["Id"].ToString());
test.Name = (string)sdr["name"];
test.LinkId = (int)sdr["LinkId"];
test.Classid = (int)sdr["ClassId"];
sdr.Close();
return test;
}
else
{
sdr.Close();
return null;
}
}
catch (Exception e)
{
throw e;
}

}


直接出异常 请高手指点

[bancxc]

很显然 select 列表中 没有 sdr中索引列名

[孟子E章]

你就
select max(Id)
出一个字段，怎么能读取到

test.Id = Convert.ToInt32(sdr["Id"].ToString());
test.Name = (string)sdr["name"];
test.LinkId = (int)sdr["LinkId"];
test.Classid = (int)sdr["ClassId"];

这4个字段的内容呢？

[孟子E章]

String sql = "select max(Id) from test3 where linkid=@linkid" ;
SqlDataReader sdr = DBHelper.GetReader(sql,new SqlParameter("@linkid",linkid));
if (sdr.Read())
{
int maxID = 0;
if(sdr[0]!=DBNull.Value)
{
maxID = ConvertToInt32(sdr[0].ToString());

}

sdr.Close();
sql = "select * from test3 where Id=" + maxID ;
sdr = DBHelper.GetReader(sql,new SqlParameter("@linkid",linkid));
if (sdr.Read())
{
Test test = new Test();

test.Id = Convert.ToInt32(sdr["Id"].ToString());
test.Name = (string)sdr["name"];
test.LinkId = (int)sdr["LinkId"];
test.Classid = (int)sdr["ClassId"];
sdr.Close();
return test;
}
else
{
sdr.Close();
return null;
}

}

[wjhx]

[Quote=引用 2 楼 net_lover 的回复:]
你就
select max(Id)
出一个字段，怎么能读取到

test.Id = Convert.ToInt32(sdr["Id"].ToString());
test.Name = (string)sdr["name"];
test.LinkId = (int)sdr["LinkId"];
test.Classid = (int)sdr["ClassId"];
……
[/Quote]
顶一下

[qqrto]

支持2楼，楼主你的sql语句中缺少了那些下面要用到的字段，把它们都补上吧

[hoojo]

数组越界了，看看索引下标对不对