Summary

This chapter focused on presenting data using the SELECT statement. It began with an introduction to reading data from existing tables using the simplest form of the SELECT statement. It then explained how to specify a list of columns, provide an alias, limit the result size, sort results for displaying, and select distinct values. The WHERE clause was then introduced to filter query results based on specific conditions, including using Boolean operators (=, >, >=, <, <=, <>, and !=) and logical operators (AND/OR/NOT), IN/NOT IN, and IS NULL/IS NOT NULL. The query logic for handling NULL values was also explained. With these skills, you will be able to query any table with desired conditions and selections to gain insights into the data.

Often, you will need to transform the data so that it is easier to understand. For example, you may want to get the current date, or to filter string fields based on the combination of words. This requires further data...