SQL Playground

Welcome to your interactive SQL laboratory, Almira! Write queries, see real-time visualizations, and master database skills through hands-on practice.

Write Your SQL Query

Results

Results will appear here after you run a query.

Example Queries

View all students

SELECT * FROM students;

Find students from Berlin

SELECT name, age FROM students WHERE city = 'Berlin';

Find Almira's grades

SELECT students.name, grades.subject, grades.score 
FROM students 
JOIN grades ON students.id = grades.student_id 
WHERE students.name = 'Almira';

Average scores by subject

SELECT subject, AVG(score) as average_score 
FROM grades 
GROUP BY subject 
ORDER BY average_score DESC;

Interactive Database Schema

students

Column Name Data Type Description
id INTEGER Primary key
name TEXT Student's name
age INTEGER Student's age
city TEXT City of residence
grade INTEGER Grade level (e.g., 10)

grades

Column Name Data Type Description
id INTEGER Primary key
student_id INTEGER Foreign key to students.id
subject TEXT Subject name
score INTEGER Score (0-100)

books

Column Name Data Type Description
id INTEGER Primary key
title TEXT Book title
author TEXT Book author
year INTEGER Publication year
category TEXT Book category

Relationship Diagram

SQL Tips for Almira

SELECT Statements

Basic SELECT:

SELECT column1, column2 FROM table_name;

Select all columns:

SELECT * FROM table_name;

Select with condition:

SELECT * FROM students WHERE age > 15;

JOIN Operations

Basic JOIN:

SELECT * 
FROM table1 
JOIN table2 ON table1.id = table2.table1_id;

Example with our tables:

SELECT students.name, grades.subject, grades.score
FROM students
JOIN grades ON students.id = grades.student_id;

Filtering & Sorting

WHERE clause:

SELECT * FROM books WHERE year > 2010;

ORDER BY clause:

SELECT * FROM students ORDER BY name ASC;

LIMIT clause:

SELECT * FROM books LIMIT 5;

Aggregation Functions

COUNT function:

SELECT COUNT(*) FROM students;

AVG function:

SELECT AVG(score) FROM grades;

GROUP BY clause:

SELECT subject, AVG(score) as avg_score
FROM grades
GROUP BY subject;