Schema Exploration Skill

When to Use This Skill

Use this skill when you need to:

• Understand the database structure

• Find which tables contain certain types of data

• Discover column names and data types

• Map relationships between tables

• Answer questions like "What tables are available?" or "What columns does the Customer table have?"

Workflow

1. List All Tables

Use sql_db_list_tables tool to see all available tables in the database.

This returns the complete list of tables you can query.

2. Get Schema for Specific Tables

Use sql_db_schema tool with table names to examine:

• Column names - What fields are available

• Data types - INTEGER, TEXT, DATETIME, etc.

• Sample data - 3 example rows to understand content

• Primary keys - Unique identifiers for rows

• Foreign keys - Relationships to other tables

3. Map Relationships

Identify how tables connect:

• Look for columns ending in "Id" (e.g., CustomerId, ArtistId)

• Foreign keys link to primary keys in other tables

• Document parent-child relationships

4. Answer the Question

Provide clear information about:

• Available tables and their purpose

• Column names and what they contain

• How tables relate to each other

• Sample data to illustrate content

Example: "What tables are available?"

Step 1: Use sql_db_list_tables

Response:

The Chinook database has 11 tables:

1. Artist - Music artists
2. Album - Music albums
3. Track - Individual songs
4. Genre - Music genres
5. MediaType - File formats (MP3, AAC, etc.)
6. Playlist - User-created playlists
7. PlaylistTrack - Tracks in playlists
8. Customer - Store customers
9. Employee - Store employees
10. Invoice - Customer purchases
11. InvoiceLine - Individual items in invoices

Example: "What columns does the Customer table have?"

Step 1: Use sql_db_schema with table name "Customer"

Response:

The Customer table has these columns:

• CustomerId (INTEGER) - Primary key, unique customer ID
• FirstName (NVARCHAR) - Customer's first name
• LastName (NVARCHAR) - Customer's last name
• Company (NVARCHAR) - Company name (optional)
• Address, City, State, Country, PostalCode - Location fields
• Phone (NVARCHAR) - Phone number
• Fax (NVARCHAR) - Fax number
• Email (NVARCHAR) - Email address
• SupportRepId (INTEGER) - Foreign key to Employee table

Sample data shows customers like:

• Luís Gonçalves from Brazil
• Leonie Köhler from Germany
• François Tremblay from Canada

Example: "How do I find revenue by artist?"

Step 1: Identify tables needed

• Artist (has artist names)

• Album (links artists to tracks)

• Track (links albums to sales)

• InvoiceLine (has sales data)

• Invoice (has revenue totals)

Step 2: Map relationships

Artist (ArtistId) ↓ 1:many Album (ArtistId, AlbumId) ↓ 1:many Track (AlbumId, TrackId) ↓ 1:many InvoiceLine (TrackId, UnitPrice, Quantity)

Response:

To find revenue by artist, you'll need to:

1. Start with the Artist table
2. JOIN to Album on ArtistId
3. JOIN to Track on AlbumId
4. JOIN to InvoiceLine on TrackId
5. SUM the revenue (UnitPrice * Quantity)
6. GROUP BY artist name

This requires the query-writing skill to execute.

Quality Guidelines

For "list tables" questions:

• Show all table names

• Add brief descriptions of what each contains

• Group related tables (e.g., music catalog, transactions, people)

For "describe table" questions:

• List all columns with data types

• Explain what each column contains

• Show sample data for context

• Note primary and foreign keys

• Explain relationships to other tables

For "how do I query X" questions:

• Identify required tables

• Map the JOIN path

• Explain the relationship chain

• Suggest next steps (use query-writing skill)

Common Exploration Patterns

Pattern 1: Find a Table

"Which table has customer information?" → Use list_tables, then describe Customer table

Pattern 2: Understand Structure

"What's in the Invoice table?" → Use schema tool to show columns and sample data

Pattern 3: Map Relationships

"How are artists connected to sales?" → Trace the foreign key chain: Artist → Album → Track → InvoiceLine → Invoice

Tips

• Table names in Chinook are singular and capitalized (Customer, not customers)

• Foreign keys typically have "Id" suffix and match a table name

• Use sample data to understand what values look like

• When unsure which table to use, list all tables first