Tag: SQL
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E-Commerce Customer 360, Churn & Revenue Analytics
1. Business Problem (Industry Scenario) You are hired as a Data Scientist for an online marketplace similar to Amazon/Flipkart. The company has 3 major issues Management Questions 2. Data Source (REAL) We will use Brazilian Olist E-commerce Datasethttps://www.kaggle.com/datasets/olistbr/brazilian-ecommerce Sample Database Look, Table Purpose customers user info orders purchase header order_items product level payments payment type…
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Have you been told “Use plain SQL, its faster than ORM” ?
You might have heard this advice before, Just use SQL; no need for ORMs. At first glance, that sounds elegant. SQL is expressive, close to the metal, and avoids the “magic” of an ORM. But as systems grow, accidental complexity sneaks in, the kind that comes not from business logic, but from all the supporting…
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Introduction to DDL (Data Definition Language) in SQL
When we talk about databases, we usually think of inserting, updating, or deleting data. But before doing any of that, we must first define the structure the blueprint of how data will be stored. That’s where DDL (Data Definition Language) comes in. What is DDL? DDL stands for Data Definition Language.It is a subset of…
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Understanding Common Table Expressions (CTE) in SQL — Simplifying Complex Queries
In SQL, we often deal with queries that involve multiple subqueries, aggregations, or recursive lookups. When these start to get long and unreadable, that’s where CTE (Common Table Expressions) come in. Let’s break it down from the basics, What is a CTE? A Common Table Expression (CTE) is a temporary named result set that exists…
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PostgreSQL Backups: Protecting Your Data Like an Architect
When you run a database, your data is everything. It powers your applications, analytics, and often, your entire business.Now imagine a sudden power failure, a disk crash, or a developer accidentally executing DROP DATABASE. That’s why backups are not optional they are your safety net. In this article, we’ll break down PostgreSQL backups from the…