Query Writing Skill

When to Use This Skill

Use this skill when you need to answer a question by writing and executing a SQL query.

Workflow for Simple Queries

For straightforward questions about a single table:

1. •Identify the table - Which table has the data?
2. •Get the schema - Use sql_db_schema to see columns
3. •Write the query - SELECT relevant columns with WHERE/LIMIT/ORDER BY
4. •Execute - Run with sql_db_query
5. •Format answer - Present results clearly

Workflow for Complex Queries

For questions requiring multiple tables:

1. Plan Your Approach

Use write_todos to break down the task:

• •Identify all tables needed
• •Map relationships (foreign keys)
• •Plan JOIN structure
• •Determine aggregations

2. Examine Schemas

Use sql_db_schema for EACH table to find join columns and needed fields.

3. Construct Query

• •SELECT - Columns and aggregates
• •FROM/JOIN - Connect tables on FK = PK
• •WHERE - Filters before aggregation
• •GROUP BY - All non-aggregate columns
• •ORDER BY - Sort meaningfully
• •LIMIT - Default 5 rows

4. Validate and Execute

Check all JOINs have conditions, GROUP BY is correct, then run query.

Example: Revenue by Country

SELECT
    c.Country,
    ROUND(SUM(i.Total), 2) as TotalRevenue
FROM Invoice i
INNER JOIN Customer c ON i.CustomerId = c.CustomerId
GROUP BY c.Country
ORDER BY TotalRevenue DESC
LIMIT 5;

Quality Guidelines

• •Query only relevant columns (not SELECT *)
• •Always apply LIMIT (5 default)
• •Use table aliases for clarity
• •For complex queries: use write_todos to plan
• •Never use DML statements (INSERT, UPDATE, DELETE, DROP)