Lập báo cáo trong SQL

Before you can start building out reports to answer specific questions, you should get familiar with the data. In this chapter, you will learn how to use E:R diagrams and data exploration techniques to get a solid understanding of the data to better answer business-related questions.

Queries can get large, fast. It's important to take a logical approach when building more complicated queries. In this chapter, you will take a step-by-step approach to plan and build a complex query that requires you to combine tables in multiple ways and create different types of fields.

Although it would be nice, data in the real-world is rarely stored in an ideal way. Simply put: data can get messy. In chapter 3, you will learn how to deal with this messy data by fixing data type issues, cleaning messy strings, handling nulls, and removing duplication.

The value of reporting really shows when presenting not-so-obvious insights through complex calculations. In this chapter, you will learn how to build more complicated fields by leveraging window functions and layered calculations. You will gain hands-on experience building two advanced calculations in particular: the percent of a total calculation and the performance index calculation.