How to check unique ID in table row

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i have a table where ID column is unique not null, i want to check if i enter duplicate entry in my ID column so a message box should come.i tried many but still not get result. please help me sir
please give me some hint.

What I have tried:

SqlConnection con = new SqlConnection("Data Source=.;Initial Catalog=DelhiEMP;Integrated Security=True");
           con.Open();
           string query = "select code from countermaster2";
           SqlDataAdapter da = new SqlDataAdapter(query,con);
           DataSet ds = new DataSet();
         if( ds.Tables["countermaster2"].Rows.Find(ds.Tables["countermaster2"].Rows)==comboBox2.SelectedItem )
           {
               MessageBox.Show("Code is already exsist");
           }
          else
           {
               MessageBox.Show("enter new records");
           }

Posted 1-May-17 20:28pm

faizy001

Updated 1-May-17 20:49pm

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Comments

Debarshi Chakraborty 2-May-17 2:35am

so is your current code not working? What are you looking for? better design or correct syntax?

faizy001 2-May-17 2:40am

sir i want to my code should be run properly. i have tried many times but still not working. please do my code in correct format .

2 solutions

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**Nirav Prabtani** · Answer 1 · 2017-05-01T20:38:00

Solution 1

I think you should do it at SQL side.

SQL

IF NOT EXISTS(SELECT COLUMNNAME FROM TABLENAME WHERE COLUMNNAME=@COLUMNNAME)
BEGIN

-- do your stuff here
SELECT 'Record saved successfully' as Response

END
ELSE
BEGIN
  SELECT 'This value exists already' as Response

END

OR

SqlConnection con = new SqlConnection("Data Source=.;Initial Catalog=DelhiEMP;Integrated Security=True");
           con.Open();
           string query = "select code from countermaster2 where code = @code";
           SqlDataAdapter da = new SqlDataAdapter(query,con);
           DataSet ds = new DataSet();
        //Pass @code value in command

            if(ds.Table[0].Rows.Count > 0)
           {
               MessageBox.Show("Code is already exsist");
           }
          else
           {
               MessageBox.Show("enter new records");
           }

Excuse Typo mistakes

Let me know if still you have any query or concern for same.

Posted 1-May-17 20:38pm

Nirav Prabtani

Comments

faizy001 2-May-17 7:33am

hello sir . i applied this codes like that but it is not working . please check where . am wrong

SqlConnection con = new SqlConnection("Data Source=.;Initial Catalog=DelhiEMP;Integrated Security=True");
con.Open();
string query1 = "insert into countermaster2(code, name, type) values(@code, @name, @type)";
SqlCommand cmd = new SqlCommand(query1,con);
SqlDataAdapter da = new SqlDataAdapter(cmd);
DataSet ds = new DataSet();
cmd.Parameters.AddWithValue("@code", comboBox2.SelectedItem);
cmd.Parameters.AddWithValue("@name", textBox2.Text);
cmd.Parameters.AddWithValue("@type", comboBox1.SelectedItem);

if (ds.Tables["countermaster2"].Rows.Count>0)
{
MessageBox.Show("Code is already exsist");
}
else
{
MessageBox.Show("enter new records");
}

cmd.ExecuteNonQuery();

MessageBox.Show("Saved");

Nirav Prabtani 2-May-17 7:38am

You are just inserting values.

You have to perform as i suggest in above solution.

faizy001 2-May-17 7:34am

sir this is very important for me please solve the problem

samit kaneriya · Answer 2 · 2017-05-01T20:49:00

Solution 2

bool existDuplicate= (from DataRow dr in ds.Tables["countermaster2"].Rows where (string)dr["code"] == comboBox2.SelectedItem select dr).Any();

Posted 1-May-17 20:49pm

samit kaneriya