SqlDataReader 判空问题？

[zhaooh]

 SqlConnection myConnection = new SqlConnection(ConfigurationSettings.AppSettings["strConn"]);
            SqlCommand thisCommand = new SqlCommand("select sum(point) as count from test where stuId='" + stuId + "'and courseName='" + courseName + "'and type='" + type+ "'", myConnection);

            myConnection.Open();
            SqlDataReader thisReader = thisCommand.ExecuteReader();
            int count = 0;

            if (thisReader== null)
            {
                return 0;
            }
            if (thisReader.Read())
            {
                count = thisReader.GetInt32(0);
            }
            thisReader.Close();
            myConnection.Close();
            return count;

上述sql语句搜索无果，但thisReader却不等于null，使我retrun 0 语句无法执行，导致 count = thisReader.GetInt32(0);报错，如何在搜索无果的情况下，执行return 0;语句啊？

[HDNGO]

HasRows

[XIEWH]

看错。
没结果if (thisReader.Read())还能进去？

[patrickpan]

SqlConnection myConnection = new SqlConnection(ConfigurationSettings.AppSettings["strConn"]);
SqlCommand thisCommand = new SqlCommand("select sum(point) as count from test where stuId='" + stuId + "'and courseName='" + courseName + "'and type='" + type+ "'", myConnection);

myConnection.Open();
SqlDataReader thisReader = thisCommand.ExecuteReader();
int count = 0;

if (thisReader.GetSchemaTable().Rows.Count == 0) //修改这行就可以了。
{
return 0;
}
if (thisReader.Read())
{
count = thisReader.GetInt32(0);
}
thisReader.Close();
myConnection.Close();
return count;

[路人乙e]

if (thisReader== null)
{
return 0;
}
if (thisReader.Read())
{
count = thisReader.GetInt32(0);
}
==》
if (thisReader.Read())
{
count = thisReader.GetInt32(0);
}
else
{
return 0;
}

[路人乙e]

最好不要直接 return 0;这样的数据连接就不会关闭
else
{
count = 0;
}

[Tiger_ldy]

reader.HasRow

[wesleyluo]

[Quote=引用 5 楼 XIEWH 的回复:]
C# code if (thisReader.Read())
{
count = thisReader.GetInt32(0);
}
else
{
return 0;
}
[/Quote]
这句简洁方便。

[claymore1114]

if(thisRead.HasRows)//记录集是否为空
{
  while(thisRead.Read())
 
  {
    .....
  }
}

[niitnanfeng]

[Quote=引用 5 楼 XIEWH 的回复:]
C# codeif(thisReader.Read())
{
count=thisReader.GetInt32(0);
}else{return0;
}
[/Quote]
有颜色的问题你看见下面那回帖的编辑器了没？A下面有个红色的那个A，选中你的要加颜色的文字点A就可以了。

[llsen]

SqlConnection myConnection = new SqlConnection(ConfigurationSettings.AppSettings["strConn"]);
SqlCommand thisCommand = new SqlCommand("select sum(point) as count from test where stuId='" + stuId + "'and courseName='" + courseName + "'and type='" + type+ "'", myConnection);

myConnection.Open();
SqlDataReader thisReader = thisCommand.ExecuteReader();
int count = 0;

if (thisReader== null)
{
return 0;
}
if (thisReader.Read())
{
count = thisReader.GetInt32(0);
}
thisReader.Close();
myConnection.Close();
return count;


sqldatareader是一行一行取数据
怎么能fill(ds)那

好像也没有用if(this.reader.read())这样用的啊
这这去一条，第一条，没有得到这个的用途

这个是这么用的
ListItem newItem = new ListItem();
ListBox1.Items.Clear();
while (reader.Read()) {
newItem = new ListItem();
newItem.Text = reader["Creater"].ToString().Trim();
newItem.Value = reader["HospitalID"].ToString().Trim();
ListBox1.Items.Add(newItem);
}
用reader逐行给listbox绑定值

[llsen]

sqldatareader是一行一行取数据
怎么能fill(ds)那

好像也没有用if(this.reader.read())这样用的啊
这这去一条，第一条，没有得到这个的用途

这个是这么用的
ListItem newItem = new ListItem();
ListBox1.Items.Clear();
while (reader.Read()) {
newItem = new ListItem();
newItem.Text = reader["Creater"].ToString().Trim();
newItem.Value = reader["HospitalID"].ToString().Trim();
ListBox1.Items.Add(newItem);
}
用reader逐行给listbox绑定值

[llsen]

sqldatareader有一个isnull函数
你看下
或者是isnul

[public_private]

顶7楼

[「已注销」]

            catch (Exception ex)
            {
                Response.Write(ex.ToString());
                Response.End();
            }
            finally

[pt1314917]

//应该是这样吧？
SqlConnection myConnection = new SqlConnection(ConfigurationSettings.AppSettings["strConn"]);
            SqlCommand thisCommand = new SqlCommand("select sum(point) as count from test where stuId='" + stuId + "'and courseName='" + courseName + "'and type='" + type+ "'", myConnection);

            myConnection.Open();
            SqlDataReader thisReader = thisCommand.ExecuteReader();
            int count = 0;

            if (thisReader== null)
            {
                return 0;
                thisReader.Close();
                myConnection.Close();
            }
            if (thisReader.Read())
            {
                count = Int32.Parse(thisReader["count"].ToString());
            }
            thisReader.Close();
            myConnection.Close();
            return count;

[zhaoqiliang527]

using (SqlDataReader dr = cmdSql.ExecuteReader())
{
if (dr!=null)
{
dt.Load(dr);
}
dr.Close();
}

[Terran5]

吧你的thisReader == null改成

     if (thisReader.GetSchemaTable().Rows.Count == 0)
     { 
                return 0; 
    } 

[山茶树和葡萄树]

用 Bool 型判断？……
就两种情况：读到和没读到……
是吧？简单吧……晕……

[marsowen123]

reader.read() = true,表示读到的有内容；相反没有读到内容
if (thisReader== null)
{
return 0;
}
if (thisReader.Read())
{
count = thisReader.GetInt32(0);
}

可以修改为
if thisReader.reader()
{ count = thisReader.GetInt32(0);
}
else
{
return 0;
}

[marsowen123]

[Quote=引用 34 楼 的回复:]
C# code
SqlDataReader dr = new SqlDataReader();
if (dr.Read()) //或if (dr.HasRows)
{
//有内容
}
else
{
//无内容
}
[/Quote]

正确答案！！没看到楼上已经有人回答出来！