Are you making this #1 SQL Error?

Today I talk about SQL cardinality, which defines the relationships between two SQL tables in a database. We explore how this can lead to repeat rows which can inflate your data later on, when you plug the data into a dashboard or do analysis. Note, all patient data contained within this video is fake, and generated by Synthea. Error @6:11 a many to many will cause extra rows as well. Many to many isn't used very often though. ➡️ FREE DOWNLOAD: SQL Basics in Healthcare: https://datawizardry.academy/sql-basics-healthcare/ Point of clarification: at Covid Vaccine: 12:07, I meant to say "How many patients with Covid Vaccines did we have?" A good guide on ERDs and crow's foot notation: https://www.smartdraw.com/entity-relationship-diagram/ Check out my previous video here if you would like to learn joins: https://youtu.be/bKBR32nUeTY // ABOUT DATA WIZARDRY: Hey I'm Josh! I've been a data analyst in the healthcare industry since 2015. Join me as I teach you how to get a job as a data analyst. I do SQL, Python, Tableau, and Networking tutorials. // BECOME A CLINICAL DATA ANALYST! My course teaches you everything you need to know in just 10-12 weeks: https://datawizardry.academy/clinical_analytics_accelerator/ // FREE WEBINAR! In this 1-hour webinar, I lay out a roadmap for you to learn how to become a data analyst, and gain healthcare domain knowledge: https://datawizardry.easywebinar.live/event-registration 🔴 YouTube: https://youtube.com/@DataWizardry 🟢 TikTok: https://tiktok.com/@data.wizardry 🔵 LinkedIn: https://linkedin.com/in/joshuamatlock/ 🔗 Website: https://datawizardry.academy #sql #dataanalyst #datanalytics #healthcaretechnology #postgresql