Select using linq to exclude fields start with numbers in MVC

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How to exclude fields starting with numbers in LINQ

What I have tried:

I know we can do it in Sql as

select * from UserTable where username not  LIKE '%[0-9]%'

How to do the same in LINQ

Posted 20-Jun-19 11:08am

Divyay208

Updated 20-Jun-19 22:49pm

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BillWoodruff 21-Jun-19 4:19am

Are the Fields starting with numbers actual numeric values, or are they strings ? Do you perhaps mean exclude "Rows" ?

2 solutions

Solution 2

Assuming:

1. 'UserTable is a DataTable

2. you have added a reference to System.Data.DataSetExtensions.dll : so you can use the 'Field extension method [^]

3. the 'UserName Column is of type 'string:

IEnumerable<DataRow> data = UserTable.Rows.Cast<DataRow>()
    .Where((DataRow row) =>
        ! char.IsDigit(row.Field<string>("UserName")[0]));

Posted 20-Jun-19 22:49pm

BillWoodruff

Updated 20-Jun-19 23:36pm

v2

Comments

Maciej Los 21-Jun-19 5:07am

5ed!

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Maciej Los · Accepted Answer · 2019-06-20T21:51:00

Like operator is translated to:

C#

var data = context.UserTable.Where(x=>x.username.Contains("whatever"));

for excluding:

C#

var data = context.UserTable.Where(x=>!x.username.Contains("whatever"));

But, seems you want to use Regex, so follow this: How to: Combine LINQ Queries with Regular Expressions (C#) | Microsoft Docs[^]

Example:

C#

List<string> users = new List<string>(){"Adam", "0Barbara", "Aegon", "1Cecylia",
				"Zea", "999Robert", "H8tor", "Gre0on",};

string pattern = @"^\d.*$";
Regex r = new Regex(pattern);

var data = users.Where(u=>!r.IsMatch(u));
foreach(string s in data)
	Console.WriteLine($"{s}");

EDIT #1
You might be interested in usage of below methods too:
String.StartsWith Method (System) | Microsoft Docs[^]
String.EndsWith Method (System) | Microsoft Docs[^]