The diploma thesis focuses on SQL query optimization methods.
As an introduction to optimization, we introduce data modeling and databases. We also dedicate a chapter to the SQL language, where we list all its features, its syntax, and the way queries are written. In the next chapter, we examine a number of methods for optimizing SQL queries from the user’s point of view, i.e., the syntax itself. We make a final summary where we present the individual problematic components of the queries and ways to replace them or improve their use.
We then test the theory in practice on three different cases of varying difficulty. Given the business requirement, we implement it as an SQL query in the Snowflake environment. We then try to syntactically correct and improve the original query by referring to the presented optimization theory. After optimization, all three test cases are executed faster, so we have shown that the way queries are written affects their performance.
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