如何在C＃中使用数据表从SQL Server检索表中的数据

Question

i want to retrieve data from my database to my window that displays all information about a student in the "Student View" where I choose a studentid and then fill all the information. Thanks in advance this is my code.

Solution 1, but not effective because i have many students and its not read from my database.

public override DataTable getStudentData()
    {    
    DataTable dt = new DataTable();
    dt.Columns.Add("StudentID");
    dt.Columns.Add("FirstName");
    dt.Columns.Add("LastName");
    dt.Columns.Add("Gender");
    dt.Columns.Add("Streetadress");
    dt.Columns.Add("ZipCode");
    dt.Columns.Add("Birthdate");
    dt.Columns.Add("StudentType");
    dt.Columns.Add("City");
    dt.Columns.Add("Country");
    dt.Columns.Add("program");
    dt.Columns.Add("PgmStartYear");
    dt.Columns.Add("credits");
    dt.Rows.Add("studentid", "Firstname", "Lastname", "Gender", "Adress", "Zipcode", "Birthdate", "Studenttype ", "City", "Country", "Programname", Startyear, credits);

return dt;
}

Solution that i want to be possible is something like this:

        DataTable dt = new DataTable();
        dt.Rows.Add(["studentid"].ToString());
        dt.Rows.Add(["firstname"].ToString());
        dt.Rows.Add(["lastname"].ToString());
        dt.Rows.Add(["gender"].ToString());
        dt.Rows.Add(["birthdate"].ToString());
        dt.Rows.Add(["streetadress"].ToString());
        dt.Rows.Add(["zipcode"].ToString());
        dt.Rows.Add(["country"].ToString());
        dt.Rows.Add(["city"].ToString());
        dt.Rows.Add(["studenttype"].ToString());
        dt.Rows.Add(["programname"].ToString());
        dt.Rows.Add(["year"].ToString());

Answer 1

You can use following function to retrieve data from SQL Server

using System.Data;
using System.Data.SqlClient;

public DataTable StudentView()
{
    SqlConnection sqlCon = new SqlConnection(@"Server= localhost\SQLINSTANCENAME; Database= DBNAME; Integrated Security=True;");

    SqlDataAdapter sqlDa = new SqlDataAdapter("QUERY", sqlCon);

    DataTable dtbl = new DataTable();
    sqlDa.Fill(dtbl);

    return dtbl;
}

Replace

• SQLINSTANCENAME with your own SQL Server instance name, eg SQLEXPRESS , SQL2008
• DBNAME with your database name
• QUERY with SELECT column-list FROM your-table

Answer 2

You need some kind of a tutorial or an article about loading from Database using C#....

The suggested answer before is one way (and will work perfectly)... and you can find another way on this link :

Although since your are new to C# and still learning, i highly recommend you to follow the "Solution 2" provided in page which uses stored procedures instead of direct SQL, since its the correct way to connect to database.

Answer 3

Thank you all. I have already connected to my database and try something like this:

           try
            {
            SqlCommand read = new SqlCommand();
            read.CommandType = CommandType.Text;
            read.Connection = connect;
            read.CommandText = "SELECT * FROM [viewstudent]";
            SqlDataReader get;
            get = read.ExecuteReader();

            while (get.Read())
            {
                dt.Rows.Add(["studentid"].ToString(); get["firstname"].ToString(); get["lastname"].ToString(); get["gender"].ToString(); get["birthdate"].ToString(); get["streetadress"].ToString(); get["zipcode"].ToString(); get["country"].ToString();
                get["city"].ToString(); get["studenttype"].ToString(); get["programname"].ToString(); get["year"].ToString(); get["credits"].ToString();
            }

            MessageBox.Show("Good!");

        }
        catch (Exception e)
        {
            MessageBox.Show("Error try again!");
        }
        connect.Close();

        return dt;
    }