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SQL Essentials: A Quick Reference Guide

📑 5 slides 👁 9 views 📅 2/18/2026 📄 PDF
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Introduction to SQL Basics

SQL is a standard language for managing and querying relational databases.

Introduction to SQL Basics
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Filtering with WHERE Clause

  • The WHERE clause extracts records that meet a specified condition.
  • Example: WHERE Salary > 2500 returns customers earning more than 2500.
  • Result: Filters rows, e.g., only John and David live in New York.
Filtering with WHERE Clause
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Grouping with GROUP BY

  • GROUP BY aggregates data by one or more columns, often with COUNT, SUM, etc.
  • Example: GROUP BY City shows customer counts per city.
  • Result: New York has 2 customers, London and Paris have 1 each.
Grouping with GROUP BY
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Sorting with ORDER BY

  • ORDER BY sorts results in ascending (ASC) or descending (DESC) order.
  • Example: ORDER BY Salary DESC lists customers from highest to lowest salary.
  • Result: David (4000), Mary (3000), Sara (2500), John (2000).
Sorting with ORDER BY
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Summary & Key Takeaways

  • SQL clauses like WHERE, GROUP BY, and ORDER BY are fundamental for data querying.
  • Filter, aggregate, and sort data efficiently for actionable insights.
  • Practice with real tables to master these essential SQL skills.
Summary & Key Takeaways
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