C# - 如何通知用户是否已经向mysql插入值

本文关键字：是否 mysql 插入 用户 何通知 通知 | 更新日期: 2023-09-27 18:36:02

是否可以

在 C# 中提醒用户（使用 MessageBox）并return;他是否将相同的值插入具有唯一约束的列？我在姓氏、名字和中间名中都有唯一的。

String command = "INSERT IGNORE INTO studentstbl (LastName, FirstName, MiddleInitial, Address, Age, Birthday, Gender, Guardian, ContactNumber, Year, IsEnrolled) VALUES (@lastname, @firstname, @middleinitial, @address, @age, @birthday, @gender, @guardian, @contactnumber, @year, 0);";
                MySqlCommand cmd = new MySqlCommand(command, conn);
                cmd.Parameters.AddWithValue("@lastname", lastnametxt.Text);
                cmd.Parameters.AddWithValue("@firstname", firstnametxt.Text);
                cmd.Parameters.AddWithValue("@middleinitial", middleitxt.Text);
                cmd.Parameters.AddWithValue("@address", addresstxt.Text);
                cmd.Parameters.AddWithValue("@age", agetxt.Text);
                cmd.Parameters.AddWithValue("@birthday", birthdaypicker.Text);
                cmd.Parameters.AddWithValue("@gender", gendercmb.Text);
                cmd.Parameters.AddWithValue("@guardian", guardiantxt.Text);
                cmd.Parameters.AddWithValue("@contactnumber", contactnumtxt.Text);
                cmd.Parameters.AddWithValue("@year", yearcmb.Text);
                try
                {
                    conn.Open();
                    cmd.ExecuteNonQuery();
                    reset();
                    MessageBox.Show("Student successfully registered! You can now proceed to Payment to enroll student.");
                    conn.Close();
                }
                catch (Exception ex)
                {
                    MessageBox.Show(ex.Message);
                }

C# - 如何通知用户是否已经向mysql插入值

您要么必须先运行查询进行检查，要么从查询中删除"IGNORE"，以便捕获错误。如果你去掉"IGNORE"，你可以捕获更具体的MySqlException并检查错误号。1062 表示存在唯一密钥冲突。MySQL文档有错误号的完整列表。像这样：

catch (MySql.Data.MySqlClient.MySqlException ex)
{
    switch (ex.Number)
    {
        case 0:
            MessageBox.Show("Cannot connect to server.  Contact administrator");
            break;
        case 1045:
            MessageBox.Show("Invalid username/password, please try again");
            break;
        case 1062:
            MessageBox.Show("Name already exists");
    }
}
finally
{
    //Since you've taken the ignore off you can run whatever you wanted to run here.
}
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