将数据从数据库提取到组合框中及其值 C#
本文关键字:组合 数据 数据库 提取 | 更新日期: 2023-09-27 18:31:27
美好的一天,我的数据库中有一个表 类
classid | class
1 JSS 1
2 JSS 2
3 JSS 3
4 SSS 1
5 SSS 2
6 SSS 3
在我的组合框中,我获取了类列并将其值设置为类 id,但现在当表单加载时,它只在组合框中显示 JSS 1,留下 JSS 2 - SSS 3。
这是我的代码
SqlConnection con = new SqlConnection(@"Data Source=.'SQLEXPRESS;AttachDbFilename=C:'Users'Solutions'Desktop'My Work'ExamProject'Project DataBase File For Exam'EExamDB.mdf;Integrated Security=True;Connect Timeout=30;User Instance=True");
bool classHaveBeenAdded = false;
void ClassCombo()
try
{
con = new SqlConnection(Properties.Settings.Default.MyConnection);
cmd = new SqlCommand("SELECT * FROM Classes", con);
cmd.Connection.Open();
SqlDataReader readClass = cmd.ExecuteReader();
ArrayList ClassList = new ArrayList();
if (readClass.Read())
{
ClassList.Add(new AddValue(readClass.GetString(1), readClass.GetInt32(0)));
}
readClass.Close();
cmd.Connection.Close();
this.comboBoxClassID.DataSource = ClassList;
this.comboBoxClassID.DisplayMember = "Display";
this.comboBoxClassID.ValueMember = "Value";
classHaveBeenAdded = true;
}
catch (Exception ex)
{
MessageBox.Show(ex.Message);
}
}
public class AddValue
{
public string m_Display;
public int m_Value;
public AddValue(string Display, int Value)
{
m_Display = Display;
m_Value = Value;
}
public string Display
{
get { return m_Display; }
}
public int Value
{
get { return m_Value; }
}
}
您没有用于从数据库中读取值的循环:
if (readClass.Read())
{
ClassList.Add(new AddValue(readClass.GetString(1), readClass.GetInt32(0)));
}
应该是:
while (readClass.Read())
{
ClassList.Add(new AddValue(readClass.GetString(1), readClass.GetInt32(0)));
}
试试这个:-
void ClassCombo()
try
{
con = new SqlConnection(Properties.Settings.Default.MyConnection);
cmd = new SqlCommand("SELECT * FROM Classes", con);
cmd.Connection.Open();
SqlDataReader readClass = cmd.ExecuteReader();
ArrayList ClassList = new ArrayList();
int i=0;
while (readClass.Read())
{
ClassList.Add(readClass["class"].ToString());
i++;
}
readClass.Close();
cmd.Connection.Close();
this.comboBoxClassID.DataSource = ClassList;
this.comboBoxClassID.DisplayMember = "Display";
this.comboBoxClassID.ValueMember = "Value";
classHaveBeenAdded = true;
}
catch (Exception ex)
{
MessageBox.Show(ex.Message);
}
}