SQL Query Expert — DBX Studio Skill

SQL Query Expert — DBX Studio

This project supports multiple database backends via user connections. Always write dialect-appropriate SQL.

Supported Dialects

| Dialect | Provider | |---------|----------| | PostgreSQL | Default / Railway | | Snowflake | Via MCP connector | | BigQuery | Via MCP connector | | Databricks | Via MCP connector | | MySQL | Via connection string | | SQLite | Via connection string |

Query Patterns

Safe SELECT with limit

Always add LIMIT unless the user explicitly wants all rows:

SELECT * FROM "schema"."table" LIMIT 100;

CTEs for complex queries

WITH ranked AS (
  SELECT *, ROW_NUMBER() OVER (PARTITION BY category ORDER BY created_at DESC) AS rn
  FROM orders
)
SELECT * FROM ranked WHERE rn = 1;

Aggregations

SELECT
  DATE_TRUNC('month', created_at) AS month,
  COUNT(*) AS total,
  SUM(amount) AS revenue
FROM orders
GROUP BY 1
ORDER BY 1 DESC;

Window Functions

SELECT
  user_id,
  amount,
  SUM(amount) OVER (PARTITION BY user_id ORDER BY created_at) AS running_total
FROM transactions;

Tool Usage in DBX Studio AI

The AI has access to these tools — always use them rather than guessing:

| Tool | When to Use | |------|-------------| | read_schema | First call — understand table structure | | get_table_data | Preview rows before writing complex queries | | execute_query | Run SELECT queries (SELECT/WITH only) | | describe_table | Get column details, FK relationships | | get_table_stats | Row counts, distributions | | generate_chart | Visualize query results |

Query Safety Rules

Only SELECT and WITH (CTEs) are permitted via execute_query
Always quote identifiers: "schema"."table"."column"
Add LIMIT automatically unless the user asks for all data
Validate table/column names exist via read_schema or describe_table first

Response Format

Execute tool to get data
Answer the user's question directly with the result
Show SQL in ```sql blocks only if the user asks "how" or "show me the query"
Present numbers clearly: "There are 1,247 orders this month"

Agent Skills: SQL Query Expert — DBX Studio

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