How can i select an autoincremented identity column whose value have to be used in another table.

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hai..
For example i have 2 tables person1,data the id of person1 is set as autoincremented and there is another column named description when description is added to table desc id should be inserted to the second table data.whose value is same as id in person1.can u please help me...Here am attaching the code..
Thanks in advance..

C#

namespace WpfApplication1
{
    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, RoutedEventArgs e)
        {
            SqlConnection con = new SqlConnection("Data Source=.;Initial Catalog=book;User ID=sa;Password=nest123@!");
            con.Open();


            string query = "insert into person1(description) values('" + textBox3.Text + "')";
            
            SqlCommand cmd = new SqlCommand(query, con);
            cmd.ExecuteNonQuery();

            try
            {
                SqlCommand cm = new SqlCommand("select Id from person1 where description='" + textBox3.Text + "'",con);
                SqlDataReader rd = cm.ExecuteReader();

                while (rd.Read())
                {
                    string str = rd["Id"].ToString();

                }
                SqlCommand cmd2 = new SqlCommand("insert into data (name,age,desc_id) values('" + textBox1.Text + "','" + textBox2.Text + "','+str+')");
            }

            catch (SqlException ex)
            {
            }
        }
        
    }
}

Posted 13-Jan-13 23:17pm

A C swathi

Updated 13-Jan-13 23:24pm

Vani Kulkarni

v2

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Vani Kulkarni · Answer 1 · 2013-01-13T23:28:00

Solution 1

In C#, right after your SQL Statement write "SELECT SCOPE_IDENTITY();" so your code would be:

C#

Insert into TABLE (...) values (...); SELECT SCOPE_IDENTITY();

Instead of ExecuteNonQuery() use ExecuteScalar().
i.e.,

C#

Decimal id = (Decimal)cmd.ExecuteScalar(); // You can now use Id for your further insert statements.

See if it works.

Posted 13-Jan-13 23:28pm

Vani Kulkarni

Updated 14-Jan-13 0:53am

v3

Comments

OriginalGriff 14-Jan-13 5:38am

Um. Our solutions are very similar, but yours will give an InvalidCastException - the return value will be a decimal, not an int. Try it. See if it works... :laugh:

Vani Kulkarni 14-Jan-13 6:51am

Just tried it. My bad. But this works on 1.1 version. Is it a bug?

OriginalGriff 14-Jan-13 7:17am

Probably a tightening up of the rules (or a more rigid interpretation of the rules) rather than a bug - I haven't used .NET V1 for a very long time so I can't really check easily! :laugh:

OriginalGriff · Answer 2 · 2013-01-13T23:36:00

Please, do not do it like that! Do not concatenate strings to build a SQL command. It leaves you wide open to accidental or deliberate SQL Injection attack which can destroy your entire database. Use Parametrized queries instead.

Secondly, the easiest way to do that is to use a single command:

C#

using (SqlConnection con = new SqlConnection(strConnect))
    {
    con.Open();
    using (SqlCommand com = new SqlCommand("INSERT INTO MyTable (myColumn1, myColumn2) VALUES ('XXX', 666) SELECT SCOPE_IDENTITY()", con))
        {
        decimal d = (decimal) com.ExecuteScalar();
        }
    }

d will contain the ID you just assigned.