Store text file into mysql Database in c#

Try cleaning the mess:

private void button1_Click(object sender, EventArgs e)
{
    string[] lines = File.ReadAllLines("D:\\out.txt");
    foreach (var line in lines)
    {
        var data = line.Split(new[] { ',' }, 4);
        int posId = int.Parse(data[0].Trim());
        double pos = double.Parse(data[1].Trim());
        double neg = double.Parse(data[2].Trim());
        string word = data[3].Trim();
        StoreRecord(posId, pos, neg, word);
    }
}

private void StoreRecord(int posId, double pos, double neg, string word)
{
    var conStr = "server=localhost; database=zahid; password=zia; User Id=root;";
    using (var connection = new MySqlConnection(conStr)) 
    using (var command = connection.CreateCommand())
    {
        connection.Open();
        command.CommandText = 
        @"INSERT INTO score 
            (POS_ID, Pos, Neg, Word) 
          VALUES 
            (@posId, @pos, @neg, @word)";
        command.Parameters.AddWithValue("@posId", posId);
        command.Parameters.AddWithValue("@pos", pos);
        command.Parameters.AddWithValue("@neg", neg);
        command.Parameters.AddWithValue("@word", word);
        command.ExecuteNonQuery();
    }
}

Things to notice:

• separating the database insert logic into a dedicated method to avoid doing parsing and db inserts in the same place
• usage of using statemenets to properly dispose IDisposable resources such as connections and commands
• usage of parametrized queries to avoid SQL injection

Also you probably don't want to be rolling your own CSV parser using String.Split but use a real CSV parser instead.

If the CSV file is big you could read it one line at a time to avoid loading it in memory at once:

private void button1_Click(object sender, EventArgs e)
{
    using (var stream = File.OpenRead("D:\\out.txt"))
    using (var reader = new StreamReader(stream))
    {
        string line;
        while ((line = reader.ReadLine()) != null)
        {
            var data = line.Split(new[] { ',' }, 4);
            int posId = int.Parse(data[0].Trim());
            double pos = double.Parse(data[1].Trim());
            double neg = double.Parse(data[2].Trim());
            string word = data[3].Trim();
            StoreRecord(posId, pos, neg, word);
        }
    }
}