LINQ Query to search for users with partial name - sql

Question

I have this SQL query:
SELECT
*
FROM
employeeTable
WHERE
(
concat(first_name, ' ', last_name) like concat('%', replace(#MatchString, ' ', '%'), '%')
or
concat(last_name, ' ', first_name) like concat('%', replace(#MatchString, ' ', '%'), '%')
)
It works perfectly by searching both name and last name with partial values., by searching users with partial strings. So for example:
"ric jon" will find Rick Jones, Richard Jonesy, and Jonathan Prichter.
I have the following Linq Query, using Entity Framework:
from employee in context.Employee
where employee.first_name.Contains(matchString)
|| employee.last_name.Contains(matchString)
select employee
But the string "ric jon" does not find anything.
I can't seem to make that linq query work the same as the SQL query.

Answer 1

That SQL wouldn't in fact find those records you sampled with the given "ric jon". What you are asking for is a special filter which IMHO requires a function that is not natively supported by the backend (you didn't specify your backend but anyway at least I don't know a backend that would support this natively). Something like this would work (note that you are getting the Employee records to local, this is not done at backend level):
Func<Employee, string[], bool> match = (emp, _parts) => {
return
((emp.FirstName.IndexOf(_parts[0],StringComparison.CurrentCultureIgnoreCase ) != -1) &&
(_parts.Length == 1 || emp.LastName.IndexOf(_parts[1], StringComparison.CurrentCultureIgnoreCase) != -1)) ||
((_parts.Length == 1 || emp.FirstName.IndexOf(_parts[1], StringComparison.CurrentCultureIgnoreCase) != -1) &&
(emp.LastName.IndexOf(_parts[0], StringComparison.CurrentCultureIgnoreCase) != -1));
};
string search = "ric jon";
var result = context.Employee.AsEnumerable()
.Where(n => match(n, search.Split()));
Update:
You can use this one which would be supported by many backends:
string search = "ric jon";
string[] parts = search.ToLowerInvariant().Split();
string p1 = parts.Length < 1 ? "" :parts[0];
string p2 = parts.Length < 2 ? "" :parts[1];
var result = context.Employee.Where(n =>
((n.FirstName.ToLowerInvariant().Contains(p1) &&
n.LastName.ToLowerInvariant().Contains(p2))) ||
((n.FirstName.ToLowerInvariant().Contains(p2) &&
n.LastName.ToLowerInvariant().Contains(p1))));