Truncate Datacolumn C#

Question

I am using C#.

I have ODBC DSN connection that I bring into DataTable. Column One is "BRANCH".

Example:

BRANCH-----| TYPE-----| ID-----|

1V--------------|   R-----------|   ZZ

1A--------------|   R-----------|   ZZ

3---------------|   W-----------|   VW

2V--------------|   R-----------|   VW

1---------------|   R-----------|   NI

4---------------|   I-----------|   MA

3B--------------|   R-----------|   SZ

I want to change column one so it only contains the first character.

It would look like this.

BRANCH-----| TYPE-----| ID-----|

1---------------|   R-----------|   ZZ

1---------------|   R-----------|   ZZ

3---------------|   W-----------|   VW

2---------------|   R-----------|   VW

1---------------|   R-----------|   NI

4---------------|   I-----------|   MA

3---------------|   R-----------|   SZ

Please help I have tried many examples, but I can't make it work.

Answer 1

Based on your need to create a column using an Expression, you can just use substring in your expression. See MSDN info on DataColumn.Expression

I believe that the first character is at Index 1

dcUnits.Expression = string.Format("SUBSTRING({0}, 1, 1)+''+{1}+''+{2}", "BRANCH", "TYPE", "ID");

Answer 2

I used RegEx to get all the digits so if you have a two digit number it will work. If it doesn't work try the index number From : row["BRANCH"] To : row[0]

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Data;
using System.Text.RegularExpressions;

namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            DataTable dt = new DataTable();
            dt.Columns.Add("BRANCH", typeof(string));
            dt.Columns.Add("TYPE", typeof(string));
            dt.Columns.Add("ID", typeof(string));

            dt.Rows.Add(new object[] { "1V", "R", "ZZ"});
            dt.Rows.Add(new object[] { "1A", "R", "ZZ"});
            dt.Rows.Add(new object[] { "3", "W", "V"});
            dt.Rows.Add(new object[] { "2V", "R", "VW"});
            dt.Rows.Add(new object[] { "1", "R", "NI"});
            dt.Rows.Add(new object[] { "4", "I", "MA"});
            dt.Rows.Add(new object[] { "1B", "R", "SZ"});

            foreach (DataRow row in dt.AsEnumerable())
            {
                row["BRANCH"] = Regex.Match(row["BRANCH"].ToString(), "\\d+").Value.ToString();
            }

        }
    }
}
​

Answer 3

Loop through your DataTable and reset the BRANCH value in each row.

        foreach (DataRow row in dt.Rows)
        {
            row["BRANCH"] = row["BRANCH"].ToString().Substring(0,1);
            Console.WriteLine(row["BRANCH"].ToString());
        }

Here is a full working version with the data you provide: https://dotnetfiddle.net/pJzeAO

Note: my reset code is different from previous answer that it resets it to the "first character" not numeric value. I believe "first character" is what you asked for in your question.

Both options are there. Use what fits your situation. Hope it helps.