SQL for Beginners and Data Analysis

SQL is the language you use to ask questions of data that lives in a relational database. This course teaches it from the ground up on **PostgreSQL 16**, the open-source database used across Ultiblob's own platforms, and it teaches SQL the way analysts actually use it: to answer business questions. You work in a terminal with `psql` against `ultishop`, a synthetic online-retail database with about 2,000 customers, 12,000 orders, 25,000 order lines, payments and support tickets. The data was generated for this course and contains the kinds of flaws real data has: missing e-mails, inconsistent casing, duplicate accounts, impossible dates and payments that do not match their orders. You learn to find those problems and to publish clean views that the rest of your analysis can trust. Across ten lessons you move from `SELECT`, filtering and sorting through calculations, aggregation and joins, then into subqueries, common table expressions and window functions (rankings, running totals, month-over-month change, cohort questions). Two lessons are about working like an analyst: profiling and cleaning data, and turning a question into sanity-checked queries, a CSV export and a written finding. The last lesson covers modifying data safely inside transactions, adding constraints and indexes, and knowing when not to touch a production database. The final project is a quarterly business review: eight business questions about `ultishop` answered with SQL, a CSV export and a one-page findings note, graded against a rubric and automated checks. Every query in the course was executed against PostgreSQL 16.15 and the output you see is the output that was observed.