How to Replicate SQL's 'IN' Statement Using LINQ's Contains() Method?

Linq Version of SQL "IN" Statement

In SQL, the "IN" statement is commonly used to query data based on a list of values. In LINQ, there are several ways to achieve similar functionality, including using the Contains() method.

To write a LINQ query that matches items based on a list of tags using the Contains() method, one can use the following approach:

Define an array or list of the desired tag IDs:

var TagIds = new int[] {2, 3, 4, 7};

Create a query that selects the items that match the specified tag IDs:

var q = from map in Context.TagMaps 
        where TagIds.Contains(map.TagId)
        select map.Items;

In this query, the Contains() method is used to check if the TagId of the current row in the TagMap table is included in the TagIds array. If it is included, the corresponding row in the Items table is selected.

The resulting query will generate an "IN (12, 32, 42)" clause in the SQL statement that is executed against the database, efficiently filtering the results based on the specified tag IDs.

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