Add Log SQL Queries Executed By ActiveRecord as a rails til

README.md

@@ -10,7 +10,7 @@ smart people at [Hashrocket](http://hashrocket.com/).
 For a steady stream of TILs from a variety of rocketeers, checkout
 [til.hashrocket.com](https://til.hashrocket.com/).
 
-_851 TILs and counting..._
+_852 TILs and counting..._
 
 ---
 
@@ -512,6 +512,7 @@ _851 TILs and counting..._
 - [Hash Slicing](rails/hash-slicing.md)
 - [Ignore Poltergeist JavaScript Errors](rails/ignore-poltergeist-javascript-errors.md)
 - [List The Enqueued Jobs](rails/list-the-enqueued-jobs.md)
+- [Log SQL Queries Executed By ActiveRecord](rails/log-sql-queries-executed-by-activerecord.md)
 - [Mark A Migration As Irreversible](rails/mark-a-migration-as-irreversible.md)
 - [Make ActionMailer Synchronous In Test](rails/make-action-mailer-synchronous-in-test.md)
 - [Mark For Destruction](rails/mark-for-destruction.md)

rails/log-sql-queries-executed-by-activerecord.md

@@ -0,0 +1,28 @@
+# Log SQL Queries Executed By ActiveRecord
+
+When entering ActiveRecord statements in a Rails console, it can be useful to
+see what SQL queries are being executed under the hood.
+
+```ruby
+> Book.first
+  Book Load (25.6ms)  SELECT  "books".* FROM "books" ORDER BY "books"."id" ASC LIMIT $1  [["LIMIT", 1]]
+=> #<Book:0x00007f824ec6ff98
+```
+
+Notice the line right after the statement shows the corresponding `select`
+query.
+
+If you aren't seeing this line of SQL, then you'll need to turn on logging for
+ActiveRecord. For instance, your test environment may not be configured to log
+the SQL.
+
+Right in your console, try running the following line:
+
+```ruby
+> ActiveRecord::Base.logger = Logger.new(STDOUT)
+```
+
+Enter an ActiveRecord statement, you should now be seeing the corresponding SQL
+queries.
+
+[source](https://stackoverflow.com/a/2936016/535590)