JSON-zu-SQL-CREATE-TABLE- und DDL-Generator

You are an experienced full-stack web developer. Build a web tool called "JSON-zu-DDL-Generator" that meets the requirements below.

## Goal

Build a tool that generates database CREATE TABLE statements from a JSON sample.

## Core features

- Choose MySQL, PostgreSQL, SQL Server or Oracle
- Infer column types from values
- Choose a primary key
- Option to map nested objects and arrays to child tables or JSON columns
- Copy result

## Inputs

- A JSON object or array of objects
- Database, table name, primary key

## Outputs

- CREATE TABLE SQL
- Reason for each inferred type

## Edge cases and handling rules

- Pick the widest type across rows (int + decimal → DECIMAL)
- Infer date/time types from ISO 8601 strings
- Allow NULL where null values appear
- Respect each database's identifier quoting and reserved words

## Implementation requirements

- Build it as a single page (HTML, CSS, JavaScript) that runs entirely in the browser, and never send the user's input to a server.
- Make the UI responsive and easy to use on mobile; label every input and keep everything keyboard accessible.
- Add a Copy button for results and show clear, friendly error messages for invalid input.
- Keep the core logic in functions separate from the UI so it can be unit-tested.

## Definition of done (test cases)

- {"id":1,"price":9.9,"createdAt":"2026-10-28T09:00:00Z"} gives integer, decimal and timestamp types
- PostgreSQL output uses double-quoted identifiers
- PRIMARY KEY appears when a key is chosen

First outline your implementation plan in at most five lines, then write the complete code, and finally explain how to check the test cases above.

---
name: build-json-ddl-generator
description: Use when building or changing a JSON-zu-DDL-Generator tool. Build a tool that generates database CREATE TABLE statements from a JSON sample.
---

# Build: JSON-zu-DDL-Generator

## Goal

Build a tool that generates database CREATE TABLE statements from a JSON sample.

## Workflow

1. Review the required features, inputs and outputs below and ask about anything missing first.
2. Implement the core logic as pure functions separate from the UI.
3. Check the logic against the test cases in the verification list.
4. Build a responsive UI with an input form, a result area and a Copy button.
5. Reproduce each edge case listed under Rules and refine the error messages.

## Core features

- Choose MySQL, PostgreSQL, SQL Server or Oracle
- Infer column types from values
- Choose a primary key
- Option to map nested objects and arrays to child tables or JSON columns
- Copy result

## Inputs

- A JSON object or array of objects
- Database, table name, primary key

## Outputs

- CREATE TABLE SQL
- Reason for each inferred type

## Rules

- Pick the widest type across rows (int + decimal → DECIMAL)
- Infer date/time types from ISO 8601 strings
- Allow NULL where null values appear
- Respect each database's identifier quoting and reserved words
- Build it as a single page (HTML, CSS, JavaScript) that runs entirely in the browser, and never send the user's input to a server.

## Verification

- [ ] {"id":1,"price":9.9,"createdAt":"2026-10-28T09:00:00Z"} gives integer, decimal and timestamp types
- [ ] PostgreSQL output uses double-quoted identifiers
- [ ] PRIMARY KEY appears when a key is chosen