关于网友提出的“library.nu ajaxnet sql 返回值 null”问题疑问，本网通过在网上对“library.nu ajaxnet sql 返回值 null”有关的相关答案进行了整理，供用户进行参考，详细问题解答如下：
问题：library.nu ajaxnet sql 返回值 null
描述: 源码是这样的
[Ajax.AjaxMethod()]
public string GetUserNameReg(string str)
{
string returnStr = "请填写姓名";
if (str != null && str!= "")
{
DataSet ds = new DataSet();
SqlConnection conn = new SqlConnection();
conn.ConnectionString = "server=.; database = AjaxTest; uid = sa; pwd =52tammy";
conn.Open();
SqlCommand cmd = new SqlCommand();
cmd.Connection = conn;
cmd.CommandText = "select * from sysusers where name = '" + str + "'";
int count = (int)cmd.ExecuteScalar();
conn.Close();
if (dr.Read())
{
returnStr = "对不起，次用户名已经被使用";
return returnStr;
}
else
{
returnStr = "该用户可以注册";
return returnStr;
}
}
return returnStr;
}
返回值老是为空（null）！！！！
如果在判断dr.Read() 改为 1==1 这类的话，返回值就是正确的
到底是怎么回事啊
！！！大侠们救命啊！急急
解决方案1: 我晕,不支持颜色,从发下.
public string GetUserNameReg(string str)
{
string returnStr = "请填写姓名";
if (str != null && str!= "")
{
DataSet ds = new DataSet();
SqlConnection conn = new SqlConnection();
conn.ConnectionString = "server=.; database = AjaxTest; uid = sa; pwd =52tammy";
conn.Open();
SqlCommand cmd = new SqlCommand();
cmd.Connection = conn;
cmd.CommandText = "select count(*) from sysusers where name = '" + str + "'"; //这句改一下
int count = (int)cmd.ExecuteScalar();
conn.Close();
if (count!=0)
{
returnStr = "对不起，次用户名已经被使用";
return returnStr;
}
else
{
returnStr = "该用户可以注册";
return returnStr;
}
}
return returnStr;
}
以上介绍了“library.nu ajaxnet sql 返回值 null”的问题解答，希望对有需要的网友有所帮助。
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