Use of the common table expressions (CTE) for the solution of exercises on DML and for the majority of rating-stage's exercises on SELECT is allowed now.
Searching and bookmarks service have appeared in the site forum.
The new stage named "Puzzles" is implemented. Exercises of this stage begin with No.251 and are accessible to participants of 3rd stage.
The points earned on solving of these exercises do not give a contribution to 3-rd stage, but are included into the total number of points of rating exercises.
New service - Modelling of data - has been launched. Service allows to add the data into the database for exercises of 2/3 stages and to compare the results on these data of test solution with own query.
Updating of the forum. New features:
- Editing and removal of messages;
- A prompt reply with citing.
Third testing stage was started with exercise #139
Feedback page of visitors and participants of rating system about the site is added.
The page with the chart of the results shown by participants while solving the exercises on the second stage (SELECT) is added: chart.php . It is possible to compare your results with the results of other participants.
The book "SQL. Problems and solutions" (in Russian), which is analyzing the characteristic mistakes admitted at the solution of the first stage exercises on the site, was published in Peter Publishing Company. Order.
The new resource Books and articles on SQL is opened.
Besides other, the analysis of typical mistakes is published there for the first stage exercises.
Checking exercises on independent data is realized,
i.e. for each exercise now there is an opportunity to create own checking database.
It allows to carry out check of correctness of the solutions more effectively.