실무 SQL 완전정복 - SECTION 6 : 분석 함수 마스터하기

SECTION 6 delves into the powerful world of window functions, essential for advanced data analysis. This section provides a comprehensive understanding of how to leverage window functions for insightful data manipulation and reporting.

Here's a breakdown of the topics covered:

• Understanding Window Functions: Learn what window functions are and how they differ from traditional aggregate functions. We'll explore the crucial OVER clause and the various types of window functions available.
• Ranking with Window Functions: Master the art of ranking data using functions like RANK(), DENSE_RANK(), and ROW_NUMBER(). Understand when to use each function for accurate ranking results.
• Calculating Percentiles and Distributions: Discover how to calculate percentile ranks and cumulative distribution using functions like PERCENT_RANK(), CUME_DIST(), and NTILE(). These are invaluable for understanding data distribution.
• Aggregating with Window Functions: Explore how to effectively utilize aggregate functions within the context of window functions for sophisticated data aggregation.
• Row Numbering and Distribution Functions: Gain a deep understanding of row numbering and distribution functions like FIRST_VALUE(), LAST_VALUE(), LAG(), LEAD(), PERCENTILE_CONT(), and PERCENTILE_DISC(). These functions enable powerful comparisons and calculations across rows.
• Specifying Window Frames: Learn to precisely control the scope of your window functions. We'll compare ROWS and RANGE specifications, and explore options like BETWEEN ~ AND, UNBOUNDED PRECEDING, UNBOUNDED FOLLOWING, and frame definitions using [ROW수] PRECEDING, [ROW수] FOLLOWING, and CURRENT ROW. This allows for highly customized window function calculations.

By the end of this section, you'll be proficient in using window functions to unlock deeper insights from your data.