SQL exercises January 05, 17:10 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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Query execution plan

Here you can investigate any execution plan of SQL query retrieving data from educational databases, as well as get query total cost, number of procedural operations, and most expensive input/output and CPU estimation.
The plan - means of optimization of SQL query - is taken from SQL Server running on the site; therefore it is identical to the execution plan received by means of QA (Query Analyzer). Optimize query to take higher place in a rating by efficiency!

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