Schema — Database Schema Design Tool

A thorough CLI tool for designing, managing, and evolving database schemas. Supports table creation, column management, indexing, relationship mapping, validation, migration generation, schema diffing, and import/export — all stored locally in JSONL format.

Prerequisites

• Python 3.8+
• Bash shell
• jq (optional, for pretty JSON output)

Data Storage

All schema data is persisted in ~/.schema/data.jsonl. Each line is a JSON object representing a schema entity (table, column, index, or relation). This enables easy versioning, diffing, and portability.

Commands

Run all commands via the script at scripts/script.sh.

create

Create a new schema/database namespace.

bash scripts/script.sh create <schema_name> [--charset utf8mb4] [--engine InnoDB]

table

Create or manage a table within a schema.

bash scripts/script.sh table <schema_name> <table_name> [--if-not-exists]

column

Add, modify, or remove a column from a table.

bash scripts/script.sh column <schema_name> <table_name> <column_name> <type> [--nullable] [--default value] [--primary] [--unique] [--remove]

index

Create or drop an index on a table.

bash scripts/script.sh index <schema_name> <table_name> <index_name> <columns> [--unique] [--drop]

relation

Define a foreign-key relationship between tables.

bash scripts/script.sh relation <schema_name> <from_table.column> <to_table.column> [--type one-to-many] [--on-delete CASCADE]

validate

Validate a schema for integrity issues (missing references, orphan columns, duplicate indexes).

bash scripts/script.sh validate <schema_name>

migrate

Generate SQL migration statements from current schema state.

bash scripts/script.sh migrate <schema_name> [--format sql|json] [--dialect mysql|postgres|sqlite]

diff

Compare two schemas and show differences.

bash scripts/script.sh diff <schema_a> <schema_b>

export

Export a schema to JSON or SQL format.

bash scripts/script.sh export <schema_name> [--format json|sql|yaml]

import

Import a schema definition from a JSON file.

bash scripts/script.sh import <file_path> [--schema_name override_name]

help

Show usage information and available commands.

bash scripts/script.sh help

version

Show the current version of the schema tool.

bash scripts/script.sh version

Workflow Example

# Create a schema
bash scripts/script.sh create myapp --charset utf8mb4

# Add tables
bash scripts/script.sh table myapp users
bash scripts/script.sh table myapp posts

# Add columns
bash scripts/script.sh column myapp users id INTEGER --primary
bash scripts/script.sh column myapp users email VARCHAR --unique
bash scripts/script.sh column myapp posts id INTEGER --primary
bash scripts/script.sh column myapp posts user_id INTEGER

# Add relation
bash scripts/script.sh relation myapp posts.user_id users.id --type one-to-many

# Validate
bash scripts/script.sh validate myapp

# Generate migration
bash scripts/script.sh migrate myapp --dialect postgres

Notes

• All data is local — no database connection required for design phase.
• Schema definitions are portable via export/import.
• Validation catches common design issues before migration.
• Supports MySQL, PostgreSQL, and SQLite dialects for migration output.

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