Check for existence of value

Check the below example, this may help you.

using System;
using System.Data;

class Program
{
    static void Main(string[] args)
    {
        // create sample data
        DataTable dt = new DataTable();
        dt.Columns.Add("Col1", typeof(string));
        dt.Columns.Add("Col2", typeof(string));
        dt.Columns.Add("Col3", typeof(string));
        dt.Rows.Add("ND", "-", "B");
        dt.Rows.Add("-", "-", "D");

        // loop through each column
        foreach (DataColumn col in dt.Columns)
        {
            bool found = false;
            // loop through each row of the column
            foreach (DataRow row in dt.Rows)
            {
                // get the value of the cell
                string cellValue = row[col].ToString();
                // check if the value contains 'S' or 'D'
                if (cellValue.Contains("S") || cellValue.Contains("D"))
                {
                    found = true;
                    break; // exit the loop if 'S' or 'D' is found
                }
            }
            if (found)
            {
                Console.WriteLine($"{col.ColumnName} contains 'S' or 'D'");
                break; // exit the loop if 'S' or 'D' is found in the column
            }
            else
            {
                Console.WriteLine($"{col.ColumnName} does not contain 'S' or 'D'");
            }
        }
    }
}