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05. Verify and First Query

Verify that the database was generated correctly.

Open in a SQL Tool

If you want to use multiple DBs in a single tool, we recommend DBeaver (free, open source). It supports SQLite, MySQL, PostgreSQL, Oracle, and SQL Server.

ezQuery Coming Soon

Once ezQuery, currently in development, is released, it will become the official recommended tool for this tutorial. It will include the tutorial database as a built-in sample, allowing you to start practicing immediately after installation.

Tool How to Open
DBeaver (recommended) New Connection > SQLite > Select output/ecommerce-ko.db file
DB Browser for SQLite sqlitebrowser.org > Open Database > ecommerce-ko.db
Command line sqlite3 output/ecommerce-ko.db
Tool How to Connect
DBeaver (recommended) New Connection > MySQL > localhost:3306 > ecommerce
MySQL Workbench dev.mysql.com > New Connection > localhost:3306
Command line mysql -u root -p ecommerce
Tool How to Connect
DBeaver (recommended) New Connection > PostgreSQL > localhost:5432 > ecommerce
pgAdmin pgadmin.org > Add Server > localhost:5432
Command line psql -U postgres ecommerce

Quick Check from the Command Line

You can verify directly from the terminal without opening a GUI tool.

sqlite3 output/ecommerce-ko.db "SELECT COUNT(*) FROM customers;"

If 5230 is displayed, everything is correct.

mysql -u root -p -e "SELECT COUNT(*) FROM ecommerce.customers;"

psql -U postgres -d ecommerce -c "SELECT COUNT(*) FROM customers;"

Run Your First Query

Enter and run the following queries in your SQL tool.

Check Table List

SELECT name FROM sqlite_master
WHERE type = 'table' AND name NOT LIKE 'sqlite_%'
ORDER BY name;

SHOW TABLES;

SELECT tablename FROM pg_tables
WHERE schemaname = 'public'
ORDER BY tablename;

If the table list is displayed, everything is working correctly.

Check Data

The same query works for all three DBs:

-- Preview customer data
SELECT name, email, grade, point_balance
FROM customers
LIMIT 5;

-- Overall data volume
SELECT
    (SELECT COUNT(*) FROM customers) AS customer_count,
    (SELECT COUNT(*) FROM products) AS product_count,
    (SELECT COUNT(*) FROM orders) AS order_count,
    (SELECT COUNT(*) FROM reviews) AS review_count;

If the results display correctly, you're all set.

Automated Verification Script

Instead of manual checking, you can run the verification script to check connection, tables, views, triggers, row counts, and FK integrity all at once.

python -m src.verify.verify

python -m src.verify.verify --target mysql

python -m src.verify.verify --target postgresql

python -m src.verify.verify --all

If everything is normal, the output will look like this:

==================================================
[VERIFY] SQL Tutorial Environment Verification
==================================================
  [OK] Python 3.12.x
  [OK] File exists (80.7 MB)
  [OK] Connection successful
  [OK] 30 tables confirmed
  [OK] 18 views confirmed
  [OK] 5 triggers confirmed
  [OK] customers: 5,230 rows
  [OK] orders: 34,908 rows
  ...
  [OK] FK integrity confirmed (orders → customers)

==================================================
[OK] Verification complete: 13/13 passed
==================================================

If Verification Fails

If there are [FAIL] items, go back to the relevant step:

← 04. Advanced Generator Options Lesson 00: Introduction to SQL →