schemalens-cli

CLI for SchemaLens — compare SQL schemas and generate migrations locally.

Zero-install schema diffing from your terminal. Parse two SQL files, get a semantic diff, and generate ALTER TABLE migration scripts in PostgreSQL, MySQL, SQLite, SQL Server, or Oracle dialects.

Install

npm install -g schemalens-cli
# or use npx (no install)
npx schemalens-cli diff old.sql new.sql

Usage

schemalens diff <old.sql> <new.sql> [options]

Options

| Flag | Description | |------|-------------| | -d, --dialect <dialect> | SQL dialect: postgres (default), mysql, sqlite, mssql, oracle | | -f, --format <format> | Output format: pretty (default), json, markdown, sql | | -o, --output <file> | Write output to file instead of stdout | | -h, --help | Show help | | -v, --version | Show version |

Examples

Pretty-printed diff (default)

schemalens diff schema-v1.sql schema-v2.sql --dialect postgres

JSON output (great for CI/CD)

schemalens diff schema-v1.sql schema-v2.sql --format json

SQL migration script

schemalens diff schema-v1.sql schema-v2.sql --format sql --output migration.sql

Markdown report

schemalens diff schema-v1.sql schema-v2.sql --format markdown --output report.md

Read from stdin

cat schema-v2.sql | schemalens diff schema-v1.sql - --dialect mysql

Fail on breaking changes (CI mode)

export SCHEMALENS_STRICT=1
schemalens diff schema-v1.sql schema-v2.sql --format json
# exits with code 2 if breaking changes are detected

Output Formats

• pretty — Colorized terminal output with summary, risk score, breaking changes, and migration preview.
• json — Machine-readable JSON with diff, migration, breakingChanges, riskScore, and summary.
• sql — Ready-to-run ALTER TABLE / CREATE TABLE script.
• markdown — Human-readable report for PR descriptions or documentation.

Supported SQL

• CREATE TABLE with columns, constraints (PK, FK, UNIQUE, CHECK), and indexes
• CREATE INDEX / CREATE UNIQUE INDEX
• CREATE TYPE ... AS ENUM (PostgreSQL)
• CREATE VIEW
• CREATE TRIGGER
• CREATE FUNCTION / CREATE PROCEDURE

Exit Codes

| Code | Meaning | |------|---------| | 0 | Success, no breaking changes | | 1 | General error (invalid args, file not found, parse error) | | 2 | Breaking changes detected (only with SCHEMALENS_STRICT=1) |

Related

• SchemaLens Web App — Visual diff viewer with shareable links
• SchemaLens API — REST API for programmatic diffs
• SchemaLens GitHub

License

MIT