How to Correctly Perform LINQ Joins Using Lambda Expressions and Query Syntax?

Use Linq and Lambda expressions to connect operations

Query error:

When trying to use Linq and Lambda expressions to connect two tables, the user encounters an error when performing the following code:

Solution using linq query grammar:

<code class="language-c#">int id = 1;
var query = database.Posts.Join(
    database.Post_Metas,
    post => database.Posts.Where(x => x.ID == id),
    meta => database.Post_Metas.Where(x => x.Post_ID == id),
    (post, meta) => new { Post = post, Meta = meta }
);</code>

For users who are more familiar with SQL syntax, using linq query grammar can improve readability and error detection ability:

Solution using the linq expansion method:

<code class="language-c#">var id = 1;
var query =
   from post in database.Posts
   join meta in database.Post_Metas on post.ID equals meta.Post_ID
   where post.ID == id
   select new { Post = post, Meta = meta };</code>

For users who insist on using Lambda expressions, the original code needs to be modified with grammar:

The modified code uses the Lambda syntax to accurately perform the connection operation, allowing users to access the data after the connection on demand.

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