🎯 Schemer - Database Schema Diff Tool

A powerful, single-file C# application that compares database schemas across different environments and generates migration scripts. Supports PostgreSQL, MySQL, SQL Server, and SQLite.

✨ Features

• Lightning-fast schema comparison across all major databases
• Beautiful, colorful console output with rich formatting
• Multiple output formats: Console, SQL, JSON, Markdown
• Comprehensive change detection: tables, columns, indexes, constraints
• Production-ready migration script generation
• Zero-installation single-file deployment

🚀 Quick Start

1. Copy the Schemer.cs file to your local machine.

You can clone the repo and put the Schemer.cs file somewhere you like. Make sure you have the NET10 SDK or Runtime installed. (Currently still in preview)

2. Run a schema comparison:

You can run Schemer commands from the terminal.

Example using the test databases provided in this repository:

dotnet run schemer.cs
      --source "Data Source=schemer_source.db"
      --target "Data Source=schemer_target.db"
      --type sqlite

3. Example output

<img width="1994" height="1752" alt="image" src="https://github.com/user-attachments/assets/aa68e281-ac71-468a-baaf-fb15de5acf15" />

📋 Command Line Options

| Option | Description | Required | Default | |--------|-------------|----------|---------| | --source | Source database connection string | ✅ | - | | --target | Target database connection string | ✅ | - | | --type | Database type (postgres, mysql, sqlserver, sqlite) | ✅ | - | | --output | Output format (console, sql, json, markdown) | ❌ | console | | --tables | Comma-separated list of specific tables to compare | ❌ | all tables | | --ignore | Comma-separated list of tables/columns to ignore | ❌ | none | | --migration-name | Name for generated migration file | ❌ | auto-generated | | --verbose | Detailed output including debug information | ❌ | false |

📊 Output Formats

Console (Default)

Beautiful, colorful console output with rich formatting showing:

• Summary statistics
• Missing, extra, and modified tables
• Detailed column-level differences

SQL Migration Scripts

Generate production-ready migration scripts:

./schemer.cs ... --output sql --migration-name "update_user_schema"

JSON Reports

Machine-readable JSON format for integration with other tools:

./schemer.cs ... --output json

Markdown Documentation

Human-readable documentation format:

./schemer.cs ... --output markdown

🔧 Connection String Examples

PostgreSQL

postgres://username:password@hostname:5432/database
Host=hostname;Database=database;Username=username;Password=password

MySQL

mysql://username:password@hostname:3306/database
Server=hostname;Database=database;Uid=username;Pwd=password

SQL Server

Server=hostname;Database=database;Integrated Security=true
Server=hostname;Database=database;User Id=username;Password=password

SQLite

Data Source=database.db
Data Source=C:\path\to\database.sqlite

🛠️ Requirements

• .NET 10.0 preview
• Database-specific drivers (automatically included via NuGet packages)

📦 Dependencies

The following NuGet packages are automatically included:

• Npgsql - PostgreSQL driver
• MySqlConnector - MySQL driver
• Microsoft.Data.SqlClient - SQL Server driver
• Microsoft.Data.Sqlite - SQLite driver
• Dapper - Micro ORM
• Spectre.Console - Rich console UI
• System.CommandLine - Command line parsing
• Newtonsoft.Json - JSON serialization

🔒 Security Features

• Connection string validation with basic SQL injection prevention
• Credential masking in console output
• Timeout handling for long-running operations
• Retry logic with exponential backoff

🤝 Contributing

This is a single-file application designed for simplicity and portability. Contributions are welcome! Please ensure any changes maintain the single-file architecture.