SQL exercises
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January 05, 17:08 MSK ???-100
SQL Exercises is intended for acquiring good practical experience, which is focused on data operation, namely on SQL DML. Certain exercises for beginners are provided on the site, they are supplied with the necessary reference source on SQL syntax with a great number of examples. Apart from them, 3 rating stages are suggested, they are aimed at testing of specialists and their certification. The source is absolutely free of charge, and the certificate purchase has a voluntary basis.
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Top 100Top 100 on latest exercises"Liberal" ratingOlympic ratingTOP 100 of Learning StageRating by summation of ranksTop 10 (photos)Last-week resultsRating of second-stage exercises (average)Rating of 2nd-stage exercises (median)Author's rating
• 2nd stage rating up to exercise:
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• Rating on the exercise:
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• Optimistic rating
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Guide to Exercise Authors

You can submit your own exercises for publication on the website, whereby they shouldn't, as far as possible, replicate ideas of exercises already existing.

1. Submission Procedure
2. Possible Locations for an Exercise
3. Summary of Materials Needed for Exercise Publication
4. Exercise Transfer Rules

1. Submission Procedure
  1. - prepare the exercise text in English and the solution (to make sure your exercise can be solved at all);
  2. - send the English version of the exercise text, along with a suggestion where to place the exercise and how many points to assign for solving it, to Sergey Moiseenko for checking;
  3. - after the exercise text is approved, prepare its Russian translation and separate verification databases (if needed). Pack all that together with the solution into a single archive, and send this archive to Sergey.

Usually, the exercises are published on Friday, just before the newsletter is coming out.


2. Possible Locations for an Exercise
  1. - learning stage;
  2. - second stage. While the exercise is under discussion, its concrete location (number), as well as the new position for the exercise it is going to replace, have to be agreed upon. For instance, your exercise may receive the number 101, and the exercise previously bearing this number will then be moved to the learning stage. Exercises are discussed on the forum, with any registered portal user who solved the exercise being able to participate in the discussion;
  3. - third stage, if you are sure your exercise is an optimizing one. If later it turns out not to be the case, it can be moved to a different stage, based on the results of the discussion on the forum thread dedicated to this exercise;
  4. - exercises with numbers greater than 300. The exercise has to be put there if it isn't an optimizing one, and you have troubles designating a location for it. There is no execution time check for "301+" exercises; thus, they can't be moved to the third stage. Most of the newly submitted exercises initially land here;
  5. - DML section.

For differences between stages, see our FAQ.

If an exercise is placed outside the range of numbers accessible to its author, the latter won't have access to the respective forum thread, either; thus, he won't be able to participate in discussing his own exercise.


3. Summary of Materials Needed for Exercise Publication
  1. - information on the desired location of the exercise, as well as its difficulty rating in points;
  2. - exercise text in English;
  3. - exercise text in Russian;
  4. - MS SQL Server test query (solution to the exercise);
  5. - SQL script for inserting verification data into a separate (so-called second) database;
  6. - if necessary, SQL script for inserting data into one more (so-called third) verification database. Note that the third database is mostly used to prevent cheating and generally shouldn't contain data fundamentally different from that of the second database. It's also possible to use only the third database for verification; in this case, the common (open) database acts as the second one;
  7. - for learning stage exercises (as well as for exercises being moved to that stage), additional test queries have to be written for the following database management systems: PostgreSQL, Oracle, MySQL.

4. Exercise Transfer Rules
  • Transfer to the learning stage. Any SELECT exercise of appropriate difficulty can be moved to the learning stage.
  • Transfer to puzzles. Any exercise with solution time control can be transferred to that stage.
  • Transfer to the third stage is not possible.






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