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Model with Merise, from MCD to SQL

Meriz is an online database design tool based on the Merise method. Draw your conceptual model, validate it, then generate the logical model, physical model and SQL script. You can also use it to learn and teach database modelling.

Try it online Download for my computer

Free and open source, with no account required. Your models stay on your device unless you create an account.

Library .meriz.json

Validate Generate

Dictionary MCD MLD MPD SQL

Define each property once, then place it in at most one entity or relationship.
Property	Type	Placed in
memberNumber	integer	Member
memberName	text	Member
isbn	text	Book
title	text	Book
borrowedOn	date	Borrow

Member

memberNumberinteger

memberNametext

Book

isbntext

titletext

Borrow

borrowedOndate

0,n 1,1

Member

memberNumberprimary key

memberName

Book

isbnprimary key

title

#memberNumberforeign key

borrowedOnfrom Borrow

MemberMySQL

memberNumberINT

memberNameVARCHAR(255)

BookMySQL

isbnVARCHAR(255)

titleVARCHAR(255)

memberNumberINT

borrowedOnDATE

CREATE TABLE Member (
  memberNumber INT NOT NULL AUTO_INCREMENT,
  memberName VARCHAR(255) NOT NULL,
  PRIMARY KEY (memberNumber)
);

CREATE TABLE Book (
  isbn VARCHAR(255) NOT NULL,
  title VARCHAR(255) NOT NULL,
  memberNumber INT NOT NULL,
  borrowedOn DATE NOT NULL,
  PRIMARY KEY (isbn)
);

ALTER TABLE Book
  ADD CONSTRAINT fk_livre_adherent
  FOREIGN KEY (memberNumber) REFERENCES Member (memberNumber);

Select an entity, relationship or connection to edit it.

Validation

No issues. The model is ready to transform.

MLD Book (isbn, title, #memberNumber, borrowedOn)

A conceptual model in Meriz: entities, their relationship and cardinalities read from each entity.

The workflow

Four stages, two to build

You create the dictionary and conceptual model. Merise transformation rules generate the rest and keep it up to date automatically.

Dictionary

Define each data item once, with its type, then place it in at most one entity or relationship.

MCD

Entities, relationships and cardinalities. Validation highlights issues as you work.

Logical and physical models

Tables, foreign keys and junction tables, followed by database-specific SQL types that you can edit column by column.

SQL and code

The CREATE TABLEscript, plus Laravel migrations or Symfony entities.

Who is it for?

One tool for three uses. Choose the parts you need.

Learn

Follow the method through one worked example. Validation explains Merise rules rather than error codes, and generated SQL shows the effect of each cardinality.

Teach

Classes with invitation codes, assignment briefs and reference solutions, automatic submission comparisons, comments pinned to models and live lesson monitoring.

Work

Build and validate a model, then generate SQL and Laravel or Symfony database code. Work together on the same model when needed, with a cursor for each participant.

What makes Meriz different?

17rules
checked

Validation that explains the rules

Seventeen rules are checked continuously. Select an issue to find the affected element. A model that passes validation can be transformed.

Works across platforms

Use it in your browser with no installation, or on Windows, macOS and Linux. The model and file format are the same.

Keyboard accessible

Designed for use without a mouse, with AA contrast checks and information that never relies on colour alone.

Free and open source

Open source under the AGPL 3.0 licence. Your files belong to you, and you can use, study and adapt the software.

Start now

Nothing to install: open the editor in your browser and keep your work on your device. Desktop versions are also available for all three operating systems.

Try it online Understand the Merise method