|SQL exercises||February 01, 18:29 MSK|
For topics "Guests' book" and "Discussing certification", authorization is only enough for access.
For access to a topic of any exercise (on SELECT or DML) it is necessary to solve corresponding exercise beforehand. Such restriction of access is connected not only with participants' rating system supported at site, but reflects opinion of developers that process of training will be more fruitful if to solve exercise at first (maybe inefficiently) and then to meet the best variants of SQL queries which, besides, become also more clear. There are many things to learn there. Leaders of rating system put their solutions effective from the point of view of performance, and also simply beautiful or original.
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