如何在C＃中向SQL添加if和else

Question

我仍然是C＃的初学者，而且我使用的是Visual Studio2015。我有一个问题，因为combobox只接受索引。 我的组合框的值为“ admin，employee”，因此，如果用户选择1索引（员工），则应将其作为“员工”存储在sql位置表中，但现在它仅存储0和1。表的数据类型为nvarchar（20）*

private void aBtnSave_Click(object sender, EventArgs e)
    {
        string conString = @"Data Source=(LocalDB)\MSSQLLocalDB;AttachDbFilename=C:\Do not delete\insertUserExample.mdf;Integrated Security=True;Connect Timeout=30";
        string query = "INSERT INTO userData (firstName,lastName,userName,password,contactNo,position) values('" + this.aTxtFirstName.Text + "', '" + this.aTxtLastName.Text + "', '" + this.aTxtUserName.Text + "', '" + this.aTxtPassword.Text + "', '" + this.aTxtContact.Text + "', '" + this.aUserPosition.SelectedIndex + "');";
        SqlConnection sqlcon = new SqlConnection(conString);
        SqlCommand sqlcom = new SqlCommand(query, sqlcon);
        SqlDataReader sqlReader;

        try {
            sqlcon.Open();
            sqlReader = sqlcom.ExecuteReader();
            MessageBox.Show("User is Saved!");

            while (sqlReader.Read()) {

            }

            aTxtFirstName.Clear();
            aTxtLastName.Clear();
            aTxtUserName.Clear();
            aTxtPassword.Clear();
            aTxtContact.Clear();

        } catch (Exception ex) {
            MessageBox.Show(ex.Message);
        }

Answer 1

您可以添加变量和条件以将组合框选择的索引更改为字符串，如下所示：

var userTitleString = this.aUserPosition.SelectedIndex == 1 ? "employee" : "admin";
string query = "INSERT INTO userData (firstName,lastName,userName,password,contactNo,position) values('" + this.aTxtFirstName.Text + "', '" + this.aTxtLastName.Text + "', '" + this.aTxtUserName.Text + "', '" + this.aTxtPassword.Text + "', '" + this.aTxtContact.Text + "', '" + userTitleString + "');";

或者，您可以在向其中添加项目时将数据绑定到comboBox：

ComboBoxItem comboItem = new ComboBoxItem();
item2.Text = "Admin";
item2.Value = "Admin";

ComboBoxItem comboItem2 = new ComboBoxItem();
item2.Text = "Employee";
item2.Value = "Employee";

List<ComboBoxItem> items = new List<ComboBoxItem> { comboItem, comboItem2 };

this.yourComboBox.DisplayMember = "Text";
this.yourComboBox.ValueMember = "Value";

this.yourComboBox.DataSource = items;

private void aBtnSave_Click(object sender, EventArgs e)
    {
        ComboboxItem selectedString = (ComboboxItem)yourComboBox.SelectedItem;
        var userPosition= selectedString.Value;
        string conString = @"Data Source=(LocalDB)\MSSQLLocalDB;AttachDbFilename=C:\Do not delete\insertUserExample.mdf;Integrated Security=True;Connect Timeout=30";
        string query = "INSERT INTO userData (firstName,lastName,userName,password,contactNo,position) values('" + this.aTxtFirstName.Text + "', '" + this.aTxtLastName.Text + "', '" + this.aTxtUserName.Text + "', '" + this.aTxtPassword.Text + "', '" + this.aTxtContact.Text + "', '" + userPosition + "');";
        SqlConnection sqlcon = new SqlConnection(conString);
        SqlCommand sqlcom = new SqlCommand(query, sqlcon);
        SqlDataReader sqlReader;

        try {
            sqlcon.Open();
            sqlReader = sqlcom.ExecuteReader();
            MessageBox.Show("User is Saved!");

            while (sqlReader.Read()) {

            }

            aTxtFirstName.Clear();
            aTxtLastName.Clear();
            aTxtUserName.Clear();
            aTxtPassword.Clear();
            aTxtContact.Clear();

        } catch (Exception ex) {
            MessageBox.Show(ex.Message);
        }

class ComboBoxItem
    {
        public string Text { get; set; }
        public string Value { get; set; }
    }

Answer 2

您可以使用以下代码。

aUserPosition.SelectedItem.Text ，您将获得选定的文本，即“ Employee”或“ Admin”。

 string query = "INSERT INTO userData (firstName,lastName,userName,password,contactNo,position) values('" + this.aTxtFirstName.Text + "', '" + this.aTxtLastName.Text + "', '" + this.aTxtUserName.Text + "', '" + this.aTxtPassword.Text + "', '" + this.aTxtContact.Text + "', '" + this.aUserPosition.SelectedItem.Text + "');";

Answer 3

如果我没有误会您的意思，您想在组合框而不是索引中获取文本。 您可以尝试下面的代码吗？

aUserPosition.GetItemText(this.aUserPosition.SelectedItem)