How to filter records from DataTable for a condition "=" ?

Question

I have a datatable with columns like First Name, Middle Name, Last Name. I need to filter the records in C# for a condition like shown below.

Select * From Table Where LastName >= 'john'

How to apply this where condition and get the filtered results set that will have records whose last names are like John, Justine, K*****, L***, M***.....Z*** ( last names from J to Z as per alphabetical order)

This datatable is populated by executing a stored procedure and I can't apply the filter at stored proc level as data is encrypted in backend.

I'm able to get the results for equality operator using the below logic.

e.g.

SQL vesion: Select * From Table Where LastName like '%john%'

C# version:

var employees = ( from e in dtEmployee.AsEnumerable()
where e.Field<string>("LastName").Contains("john")
select e ).ToList();

Similarly, need to use the >= operator. How to get records for this filter condition? Can anyone please help on this?

Tapan Patel · Answer

Also if you are looking to do that in query SELECT LastName FROM Table WHERE ASCII( 'j' ) LEFT (LastName 1))

Amit Gupta · Answer

You can use IndexOf function to filter your records instead of contains. IndexOf matches your string and returns the index which gives more precise result.

Khan Abrar Ahmed · Answer

http://blogs.microsoft.co.il/bursteg/2007/10/16/linq-to-sql-like-operator/ http://codesamplez.com/database/linq-to-sql-like-operator

Ankit Sharma · Answer

Hi SriRam I have tested this code and i am getting the correct result. Please check it once var employee = (from e in dtEmployee.AsEnumerable() where String.Compare(e.Field string ( LastName ) john ) >= 0 select e).ToList();

Tapan Patel · Answer

I am not that familiar with query expression so I tried with lambda. Here is the working example. public void TestGreaterThanEqualTo( string name = john ) { List string > names = new List string > { jgfdg  kfsdff  fsdfsf  ldsfsf  ssdfdfd  tsdfsf }; var greaterthanname = names.Where(nm => nm[0] > name[0]); Debug.WriteLine(greaterthanname.Count()); //outputs 4 as expected. }

Sri Ram · Answer

Thank you Ankit for your support. Unfortunately the stackoverflow solution doesn't filter records correctly..

Ankit Sharma · Answer

Hi Please refer to below links https://stackoverflow.com/a/19603991 https://stackoverflow.com/questions/3365122/how-to-compare-a-string-column-value-in-a-linq-query Hope this helps

How to filter records from DataTable for a condition ">=" ?