[英]the result doesn't appear in listbox
請問下面的代碼有什么問題。因為它不顯示結果。 我想查看員工的姓名,每月的活動數量,然后通過除以數字來查看其平均等級。 活動的得分。 我希望你能幫助我做到這一點。 我想在列表框中查看
格式是這樣的:
Juan Dela Cruz
Count: 10
Score: 5
Grade: 2
econ = new SqlConnection();
econ.ConnectionString = emp_con;
econ.Open();
int found = -1;
string Log_User, Count, Score;
int iGrade = 0;
string n = "";
string strScore = "Score: ";
string strGrade = "Grade: ";
string strCount = "Count: ";
ecmd = new SqlCommand("SELECT Log_User, Count = COUNT(Det_Score), Score = SUM(Det_Score) FROM MEMBER M,DETAILS D WHERE D.Emp_Id = M.Emp_Id AND Month(Sched_Start) like" + "'" + comMonth.Text + "'AND Year(Sched_Start) like" + "'" + txtYear.Text + "'GROUP BY Log_User", econ);
ecmd.CommandType = CommandType.Text;
ecmd.Connection = econ;
dr = ecmd.ExecuteReader();
listBox1.Text = txtYear.Text;
listBox1.Text = comMonth.Text;
while (dr.Read())
{
Log_User = (string)dr["Log_User"];
Count = (string)dr["Count"];
Score = (string)dr["Score"];
iGrade = Convert.ToInt32(Count) / Convert.ToInt32(Score);
found += 1;
listBox1.Items.Insert(found, Convert.ToString(n));
listBox1.Items.Insert(found, Convert.ToString(strGrade) + Convert.ToString(iGrade));
listBox1.Items.Insert(found, Convert.ToString(strScore) + Convert.ToString(Score));
listBox1.Items.Insert(found, Convert.ToString(strCount) + Convert.ToString(Count));
listBox1.Items.Insert(found, Convert.ToString(Log_User));
listBox1.Items.Insert(found, Convert.ToString(n));
}
econ.Close();
}
catch (Exception x)
{
MessageBox.Show(x.GetBaseException().ToString(), "Connection Status", MessageBoxButtons.OK, MessageBoxIcon.Error);
}
我想在這里查看結果,但看不到輸出。 我的sql語句有什么問題嗎? 在MS SQL 2005中,當我運行sql時,它運行平穩,但是當我將其運行到VS 2010時,它沒有出現。
可能有幾個問題。
您是否嘗試在Sql Management Studio中運行sql語句?
他們有結果嗎?
如果是這樣,請嘗試使用
listbox1.Items.Add
而不是Insert
沒有異常錯誤,儀式嗎?
如果我是你,我會使用sqlDataAdapter
,並把所有的結果到datatable
,那么我會檢查是否datatable
有任何行。 如果是這樣,我將循環並將其添加到列表框中。
我以一種可行的方式更改了您的代碼:
econ = new SqlConnection();
econ.ConnectionString = emp_con;
econ.Open();
string Log_User, Count, Score;
int iGrade = 0;
string n = "";
string strScore = "Score: ";
string strGrade = "Grade: ";
string strCount = "Count: ";
ecmd = new SqlCommand("SELECT Log_User, Count = COUNT(Det_Score), Score = SUM(Det_Score) FROM MEMBER M,DETAILS D WHERE D.Emp_Id = M.Emp_Id AND Month(Sched_Start) like" + "'" + comMonth.Text + "'AND Year(Sched_Start) like" + "'" + txtYear.Text + "'GROUP BY Log_User", econ);
ecmd.CommandType = CommandType.Text;
ecmd.Connection = econ;
dr = ecmd.ExecuteReader();
listBox1.Items.Add(txtYear.Text);
listBox1.Items.Add(comMonth.Text);
while (dr.Read())
{
Log_User = (string)dr["Log_User"];
Count = (string)dr["Count"];
Score = (string)dr["Score"];
iGrade = Convert.ToInt32(Count) / Convert.ToInt32(Score);
listBox1.Items.Add(string.Format("{0}", n));
listBox1.Items.Add(string.Format("Grade: {0}", iGrade)));
listBox1.Items.Add(string.Format("Score: {0}", Score)));
listBox1.Items.Add(string.Format("Count: {0}", Count));
listBox1.Items.Add(Log_User);
listBox1.Items.Add(n.ToString());
}
econ.Close();
}
catch (Exception x)
{
MessageBox.Show(x.GetBaseException().ToString(), "Connection Status", MessageBoxButtons.OK, MessageBoxIcon.Error);
}
您最大的問題將是SQL語句,特別是喜歡的語句。 您無需添加%,因此除非用戶輸入,否則不會有任何結果。
另外,由於您要查找月份號,因此在這種情況下我認為不適合這樣做。
最后,應該使用參數來防止SQL注入,但是我將其保留為另一項練習。
這是您需要的最小更改:
ecmd = new SqlCommand("SELECT Log_User, Count = COUNT(Det_Score), Score = SUM(Det_Score) FROM MEMBER M,DETAILS D WHERE D.Emp_Id = M.Emp_Id AND Month(Sched_Start) = " + comMonth.Text + " AND Year(Sched_Start) = " + txtYear.Text + " GROUP BY Log_User", econ);
另外,您不需要在列表項上使用插入,而應使用添加來代替:
listBox1.Items.Add(Convert.ToString(n));
etc...
最后,如果它們包含DBNulls,則應該從數據庫中強制轉換這些值:
Log_User = dr["Log_User"] as string;
etc...
將插入替換為添加。
if (dr == null || !dr.HasRows) {
//No records found
}
else
{
listBox1.Items.Add(found, Convert.ToString(n));
listBox1.Items.Add(found, Convert.ToString(strGrade) + Convert.ToString(iGrade));
listBox1.Items.Add(found, Convert.ToString(strScore) + Convert.ToString(Score));
listBox1.Items.Add(found, Convert.ToString(strCount) + Convert.ToString(Count));
listBox1.Items.Add(found, Convert.ToString(Log_User));
listBox1.Items.Add(found, Convert.ToString(n));
}
問候
您絕對確定SQL查詢可以在SQL Mgmt studio中正確運行嗎? 您沒有在Count字段上分組(至少),因此應該得到一個匯總錯誤。
另外,您可能想要適當的加入,而不是通過WHERE子句(個人偏好)加入。
實際上,您的SQL語句似乎已損壞。 嘗試這個:
SELECT Log_User, COUNT(Det_Score) as count, SUM(Det_Score) as Score
FROM MEMBER M
JOIN DETAILS D on M.Emp_Id = D.Emp_Id
WHERE MONTH(Sched_Start) like + "' + comMonth.Text + '" AND YEAR(Sched_Start) LIKE "' + txtYear.Text '"
GROUP BY Log_User, COUNT(Det_Score) as count, SUM(Det_Score) as Score
listBox1.Items.Clear();
listBox1.Text = "";
econ = new SqlConnection();
econ.ConnectionString = emp_con;
econ.Open();
float iGrade = 0;
float Grade = 0.00F;
string Log_User;
float Count, Score;
string n = "";
string strScore = "Score: ";
string strGrade = "Grade: ";
string strCount = "Count: ";
string date = DateTime.Now.ToShortTimeString();
ecmd = new SqlCommand("SELECT Log_User, Count = COUNT(Det_Score), Score = SUM(Det_Score) FROM MEMBER M,DETAILS D WHERE D.Emp_Id = M.Emp_Id AND Log_User like" + "'" + Convert.ToString(comEmployee.Text) + "'AND Month(Sched_Start) =" + "'" + Convert.ToInt32(iMonth) + "'AND Year(Sched_Start) =" + "'" + Convert.ToInt32(txtYear.Text) + "'GROUP BY Log_User", econ);
ecmd.CommandType = CommandType.Text;
ecmd.Connection = econ;
dr = ecmd.ExecuteReader();
listBox1.Items.Add("As of " + date + ": "+ comMonth.Text + ", "+ txtYear.Text);
while (dr.Read())
{
if (dr == null || !dr.HasRows)
{
MessageBox.Show("No record found.", "Error");
}
else
{
Log_User = (string)dr["Log_User"];
Count = (dr["Count"] as int?) ?? 0;
Score = (dr["Score"] as int?) ?? 0;
try
{
iGrade = Score / Count;
Grade = iGrade * 100;
}
catch (DivideByZeroException)
{
Console.WriteLine("Exception occured");
}
listBox1.Items.Add(Convert.ToString(n));
listBox1.Items.Add(Convert.ToString(Log_User));
listBox1.Items.Add(Convert.ToString(strCount + Count));
listBox1.Items.Add(Convert.ToString(strScore + Score));
listBox1.Items.Add(Convert.ToString(strGrade + Grade));
}
}
econ.Close();
上面的代碼是我對我的問題的回答。我希望它可以對其他人有所幫助。 感謝那些幫助我解決問題的人..:D上帝保佑
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