Schema Lens

Your schema, in focus. Instant ERD from the files you already write.

Schema Lens parses your SQL migrations, Prisma schemas, Drizzle schemas, and Knex migrations and renders an interactive ERD directly inside VS Code, with no database connection required.

Features

• Interactive ERD in VS Code
  Entity-relationship diagrams with zoom and pan in a side panel next to your editor.

• File-first, multi-format support
  Works from the files you already maintain:

  • Raw SQL (.sql)
  • Prisma (schema.prisma)
  • Drizzle ORM schema files (pgTable, mysqlTable, sqliteTable)
  • Knex.js migration files (createTable etc.)

• Live reload on save
  Edit your migration or schema, hit save, and the diagram refreshes automatically.

• Visual diff mode
  Compare two schema files and see:

  • 🟢 Added tables and columns
  • 🔴 Removed tables and columns
  • 🟡 Modified tables

• Respects your theme
  Diagram styling follows your VS Code light or dark theme preferences.

Installation

From VSIX

1. Download the .vsix file from the Releases page.
2. In VS Code, open the Extensions view, open the “Views and More Actions…” menu (…), and choose Install from VSIX…. [web:135]
3. Select the downloaded .vsix file and complete the install.

From Marketplace

1. Open VS Code.
2. Go to Extensions (Ctrl+Shift+X).
3. Search for Schema Lens.
4. Click Install.

Usage

1. Open a supported schema file:
   • SQL: *.sql
   • Prisma: schema.prisma
   • Drizzle: TypeScript files with pgTable / mysqlTable / sqliteTable
   • Knex: TypeScript migration files with createTable
2. Click the ≋ ERD button in the editor title bar
   or run Schema Lens: Open ERD from the Command Palette (Ctrl+Shift+P).
3. The ERD opens in a side panel next to your code.
4. Zoom with the scroll wheel, pan by clicking and dragging the canvas.
5. Save the file to refresh the diagram with your latest changes.

Diff Mode

1. Open a schema file.
2. Run Schema Lens: Compare With… from the Command Palette.
3. Choose a second schema file to compare.
4. A diff ERD opens showing:
   • 🟢 Added tables and columns
   • 🔴 Removed tables and columns
   • 🟡 Modified tables

Supported Formats

Format	File Pattern	Parser Approach
Raw SQL	*.sql	node-sql-parser for CREATE/ALTER/FOREIGN KEY
Prisma	schema.prisma	Line-based parser for model, fields, @relation
Drizzle	*.ts with pgTable / mysqlTable / sqliteTable	TypeScript AST walk
Knex.js	*.ts with createTable	TypeScript AST walk

Limitations and Edge Cases

• Internet on first use
  Mermaid is loaded from a CDN the first time the ERD panel is opened. You can later bundle it locally if needed. [web:143]

• SQL dialect coverage
  The SQL parser targets common PostgreSQL and MySQL syntax. Vendor-specific features such as SQL Server IDENTITY may fail to parse cleanly.

• Drizzle and Knex detection
  For .ts files, Schema Lens auto-detects Drizzle vs Knex based on imports and function calls. If a file mixes both patterns, Drizzle is preferred.

• Prisma enums
  enum blocks are currently ignored and do not appear in the ERD.

• Composite foreign keys
  Fully supported in SQL parsing. ORM parsers handle the common patterns but some complex composites may not render perfectly yet.

• Views and procedures
  Views, stored procedures, and functions are not parsed or shown in the diagram.

• Very large schemas
  Diagrams with more than ~50 tables can feel heavy in the panel. Use zoom and pan to navigate large models efficiently.

• Inline SQL comments
  Complex block comments (/* ... */) inside CREATE TABLE definitions can confuse the SQL parser in some cases.