What Is the Linq Equivalent to the SQL in Operator

What is the linq equivalent to the SQL IN operator

.Contains

var resultset = from x in collection where new[] {2,3,4,5}.Contains(x) select x

Of course, with your simple problem, you could have something like:

var resultset = from x in collection where x >= 2 && x <= 5 select x

Convert a sql query having in operator to linq

The equivalent to a SQL IN clause in LINQ is a Contains statement.

IEnumerable<long> validWigetItemIds; // fill from Database or input parameters

var result = DbContext.JobItems
    .Where(ji => validWigetItemIds.Contains(ji.WidgetItemId)); // equivalent to IN clause
    // other LINQ statements as required by your usecase

Linq to Entities - SQL IN clause

You need to turn it on its head in terms of the way you're thinking about it. Instead of doing "in" to find the current item's user rights in a predefined set of applicable user rights, you're asking a predefined set of user rights if it contains the current item's applicable value. This is exactly the same way you would find an item in a regular list in .NET.

There are two ways of doing this using LINQ, one uses query syntax and the other uses method syntax. Essentially, they are the same and could be used interchangeably depending on your preference:

Query Syntax:

var selected = from u in users
               where new[] { "Admin", "User", "Limited" }.Contains(u.User_Rights)
               select u

foreach(user u in selected)
{
    //Do your stuff on each selected user;
}

Method Syntax:

var selected = users.Where(u => new[] { "Admin", "User", "Limited" }.Contains(u.User_Rights));

foreach(user u in selected)
{
    //Do stuff on each selected user;
}

My personal preference in this instance might be method syntax because instead of assigning the variable, I could do the foreach over an anonymous call like this:

foreach(User u in users.Where(u => new [] { "Admin", "User", "Limited" }.Contains(u.User_Rights)))
{
    //Do stuff on each selected user;
}

Syntactically this looks more complex, and you have to understand the concept of lambda expressions or delegates to really figure out what's going on, but as you can see, this condenses the code a fair amount.

It all comes down to your coding style and preference - all three of my examples do the same thing slightly differently.

An alternative way doesn't even use LINQ, you can use the same method syntax replacing "where" with "FindAll" and get the same result, which will also work in .NET 2.0:

foreach(User u in users.FindAll(u => new [] { "Admin", "User", "Limited" }.Contains(u.User_Rights)))
{
    //Do stuff on each selected user;
}

What is the SQL LIKE operator equivalent in LINQ having multiple % operators in the input text?

Posting the comments given by @Fabio and @CodeNotFound as answer for reference.

In EntityFramework version 6.2.0:

var users = (from usr in Context.Users
            where DbFunctions.Like(usr.Username, "%test%email%")
            select usr).ToList();

Where IN clause in LINQ

This expression should do what you want to achieve.

dataSource.StateList.Where(s => countryCodes.Contains(s.CountryCode))

IN Operator in Linq

var activeMembers = (
from member in db.ContactSet
where activeProducts.Select(x=>x.ID).Contains(member.ID));

What is the linq equivalent of the below sql query

Assuming SelectedProducts is an array of product ids (integers):

var cats = db.Categories.Where(o => SelectedProducts.Contains(o.CategoryId));
var pids = cats.Select(o => o.ProductId);

Reason: SQL IN operator is implemented oppositely in LINQ to SQL. The question highlights a common mistake in LINQ developers trying to translate from SQL, expecting an [attribute] [operator] [set] syntax.

Using an abstract set language we can highlight syntax differences

• SQL uses a "Element is included in Set" syntax
• LINQ uses a "Set contains Element" syntax

So any IN clause must be reverted using the Contains operator. It will translate to attribute IN (SET) anyways.

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