Question

I need some help in building the correct query. I have an Employees table. I need to get a list of all employees, that EENO (Employee ID) contains a string from a supplied array of partial Employee IDs.

When I use this code

// IEnumerable<string> employeeIds is a collection of partial Employee IDs
IQueryable<Employee> query = Employees;
foreach (string id in employeeIds)
{
    query = query.Where(e => e.EENO.Contains(id));
}
return query;

I will get something like:

SELECT * 
FROM Employees 
WHERE EENO LIKE '%1111111%' 
  AND EENO LIKE '%2222222%' 
  AND EENO LIKE '%3333333%' 
  AND EENO LIKE '%4444444%' 

Which doesn’t make sense.
I need “OR” instead of “AND” in resulting SQL.

Thank you!

UPDATE

This code I wrote using PredicateBuilder works perfectly when I need to include these employees.

var predicate = PredicateBuilder.False<Employee>();
foreach (string id in employeeIds)
{
    var temp = id;
    predicate = predicate.Or(e => e.EENO.Contains(temp));
}
var query = Employees.Where(predicate);

Now, I need to write an opposite code, to exclude these employees,
here it is but it is not working: the generated SQL is totally weird.

var predicate = PredicateBuilder.False<Employee>();
foreach (string id in employeeIds)
{
    var temp = id;
    predicate = predicate.And(e => !e.EENO.Contains(temp)); // changed to "And" and "!"
}
var query = Employees.Where(predicate);
return query;

It’s supposed to generate SQL Where clause like this one:

WHERE EENO NOT LIKE '%11111%'
       AND NOT LIKE '%22222%'
       AND NOT LIKE '%33333%'

But it’s not happening

The SQL generated is this: http://i.imgur.com/9MDP7.png

Any help is appreciated. Thanks.

Answer 1

I’d take a look at http://www.albahari.com/nutshell/predicatebuilder.aspx. This has a great way of building Or queries, and is written by the guy that wrote LinqPad. The above link also has examples of usage.