ID       IP
1     192.168.1.1
1     192.168.1.2
1     192.168.1.3
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SELECT DISTINCT Stuff(( 
    SELECT ','+ A2.IP FROM [td_Account_Login] A2 
    WHERE A2.ID = A1.ID 
    FOR XML Path('')) ,1, 1, '') 
    FROM [td_Account_Login] A1
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string sql = "SELECT DISTINCT Stuff(( SELECT ',' + A2.IP FROM [td_Account_Login] A2 WHERE A2.ID = A1.ID FOR XML Path('') ), 1, 1, '') FROM [td_Account_Login] A1";
            connect = new SqlConnection(strConnection);
            connect.Open();
            command = new SqlCommand(sql, connect);
            SqlDataReader reader = command.ExecuteReader();
           
            //_________________________
            
            TextWriter op = new StreamWriter(@"OpenIP.txt");
            op.WriteLine(del);
            op.Write(bat);
            while (reader.Read())
            {
            op.Write(String.Format("{0}", reader[0]));
            }
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192.168.1.1
,192.168.1.2
,192.168.1.3
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192.168.1.1 ,192.168.1.2 ,192.168.1.3  
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