Normalization and Constraints
Query Plan Analysis
Using our MySQL Database Developer online assessment test will assure your candidates’ skills in all aspects of development for MySQL using 24 highly detailed questions.
All questions represent practical, general knowledge around developing for MySQL and should be known by strong MySQL database developers.
The test is put together by the world-renowned SQLskills.com team. They’ve authored more than 65 in-depth Pluralsight courses on RDBMS topics, and have been providing high quality DBA and developer training and consulting since 1995. They are intimately familiar with all aspects of the chapters in this test and also have extensive experience interviewing Database Developer candidates for their clients.
The sub-chapters were picked after considering the broad scope of developing for MySQL, and the SQLskills team has assessed the six most vital areas to evaluate the qualifications and practical experience of a specific candidate. See all chapters to the right.
By using our MySQL Database Developer online assessment test, recruiting talented developers will be easier. You will have a significantly higher chance of employing a strong candidate, as well as eliminating the risk of hiring an under-qualified candidate who lacks real-world experience.
This online assessment test has a number of use cases:
Normalization and Constraints
An important development skill when designing a database is applying relational theory to construct a data model for the data being stored. This means a strong candidate will understand how to normalize the data so it can be efficiently stored and searched, plus how to codify the relationships between fields in different tables using appropriate constraints.
A strong developer will be able to construct a schema that accurately and efficiently represents the data model. This means choosing appropriate data types, table design, functions and procedures that don’t hinder performance, and even temporary tables used during query execution.
One of the most important tasks of a developer is choosing the index strategy for each table, taking into account the various data types and the queries that will be performed on the table. A strong candidate will also know how to choose an appropriate primary key, avoiding common performance pitfalls and behavior misconceptions, use covering indexes, and how and when to consolidate similar secondary indexes.
There are many things to consider when inserting, updating, or deleting data, including how to avoid excessive blocking, how to load data, when to use explicit transactions, when to change isolation level from the default, and how the various defaults work. A strong database developer candidate will be aware of the problems that can occur when modifying data and how to avoid them.
Probably the single most important thing a MySQL database developer does is write effective queries to select data from the database. It is therefore important that a strong candidate knows how to write a wide variety of queries, including creating cross-table selects using joins/subqueries, using aggregates, using windowing functions, dealing with NULL data, and writing search arguments to ensure indexes can be used appropriately.
Query Plan Analysis
Of course, when writing queries, a great database developer will check to make sure that the query plan that MySQL has generated is efficient. This means a strong candidate has to be familiar with query plan analysis using EXPLAIN, which includes understanding operators (their meaning and associated costs), making sure aggregates are correct, and ensuring that the most efficient access to the data is being performed, using the appropriate indexes.
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