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Lesson 1.1 · garden_shop
Lesson 1.1

What Is SQL?

SQL is a practical way to ask structured questions about rows and columns.

SQL is a language for working with tables. A table is organized into columns, which describe what each value means, and rows, which hold individual records.

A SQL query doesn't change the original table unless you use commands built for changing data. In these first lessons, queries only read data and return a temporary result.

Pattern 
select column_names
from table_name
Schema · Garden Shop Table · customers 9 columns · 20 rows
Table · customers

One row per customer. Some customers have no phone on file.

9 columns · 20 rows
customer_id int first_name text last_name text email text phone text city text state text signup_date date is_active bool
Your task

Run the starter query, then change it to show each customer's first name, last name, city, and state.

·

Run your query to inspect the result.

Expected answer
  • Columns: first_name, last_name, city, state.
  • Rows: 5 customers.
Next · 1.2 Your first SELECT →

Related

Reference
SQL SELECT Syntax

Clause order and the shape of a SELECT query.

Cheatsheet
SQL Query Basics Cheatsheet

SELECT, WHERE, ORDER BY, and LIMIT at a glance.

Error
Fix “Column Not Found” When Filtering on a SQL Alias

WHERE is evaluated before SELECT aliases exist.

Error
Fix “Syntax Error at or Near” in SQL

The parser stopped at the first word it could not use.

Error
Fix “Referenced Column Not Found” in SQL

No table in the FROM clause has that column.

Lesson
Tables, Rows, and Columns in SQL

Learn the basic shape of relational data.