InvalidOperationException：当不存在数据时尝试读取无效。 （SQL）
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void ExecuteContent()
{
StringBuilder sb = new StringBuilder();
sb.Append(\"SELECT TOP 1 @UsersID,u.Avatar,t.Date, u.Name, t.ThreadTitle, t.ThreadParagraph\");
sb.Append(\" FROM Users as u\");
sb.Append(\" INNER JOIN Threads as t ON u.UsersID = t.UsersID\");
sb.Append(\" Where @UsersID=t.UsersID\");
sb.Append(\" ORDER BY t.Date DESC\");
using (SqlConnection conn = new SqlConnection(AnswerQuestion.connectionString))
{
conn.Open();
SqlCommand sqlComm = new SqlCommand(sb.ToString(), conn);
MembershipUser CurrentUser = Membership.GetUser();
Guid i = (Guid)CurrentUser.ProviderUserKey;
sqlComm.Parameters.Add(\"@UsersID\", SqlDbType.UniqueIdentifier).Value = i;
SqlDataReader dr = sqlComm.ExecuteReader();
UserName = dr[\"Name\"].ToString();//The exception is thrown here
Image = (Image) dr[\"Avatar\"];
ThreadTitle = dr[\"ThreadTitle\"].ToString();
ThreadParagraph = dr[\"ThreadParagraph\"].ToString();
Time = (DateTime)AllQuestionsPresented.TryParse(dr[\"Date\"].ToString());
}
}
没有找到相关结果
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2 个回复
耐扫鹤胶鞭
while(dr.Read()) { serName = dr[\"Name\"].ToString();//The exception is thrown here Image = (Image) dr[\"Avatar\"]; ThreadTitle = dr[\"ThreadTitle\"].ToString(); ThreadParagraph = dr[\"ThreadParagraph\"].ToString(); Time = (DateTime)AllQuestionsPresented.TryParse(dr[\"Date\"].ToString()); }（如果您只有一个结果） 和 您应该始终在阅读器周围使用以下用途：using(dr) { while(dr.Read()) { } }这是在代码中编写查询的小技巧，使用逐字记录：var query = @\"SELECT TOP 1 @UsersID,u.Avatar,t.Date, u.Name, t.ThreadTitle, t.ThreadParagraph FROM Users as u INNER JOIN Threads as t ON u.UsersID = t.UsersID Where @UsersID=t.UsersID ORDER BY t.Date DESC\";埠仙俊
if(dr.Read()) { UserName = dr[\"Name\"].ToString();//The exception is thrown here Image = (Image) dr[\"Avatar\"]; ThreadTitle = dr[\"ThreadTitle\"].ToString(); ThreadParagraph = dr[\"ThreadParagraph\"].ToString(); Time = (DateTime)AllQuestionsPresented.TryParse(dr[\"Date\"].ToString()); }