DDL to ERD

From CREATE TABLE statements to automated PK & FK relationships in ER diagram.

Quick start

Read the blog: SQL Diagram (Part 3): SQL-to-ERD with DDL

Best practice: Some DDL syntax is currently not supported.

If you don't see the diagram, please simplify complex settings in your schema to include only column names and data types.

Example:

CREATE TABEL {{name}} (

{{name}} TYPE )

Learn SQL CREATE TABLE Statement:

CREATE TABLE users(
	id INT AUTO_INCREMENT UNIQUE PRIMARY KEY,
	username VARCHAR(255) NOT NULL,
	created_at TIMESTAMP DEFAULT NOW()
);

CREATE TABLE photos(
	id INT AUTO_INCREMENT PRIMARY KEY,
	image_url VARCHAR(355) NOT NULL,
	user_id INT NOT NULL,
	created_dat TIMESTAMP DEFAULT NOW(),
	FOREIGN KEY(user_id) REFERENCES users(id) -- 👈 Relation
);

---

Using REFERENCES

Learn more: https://www.w3schools.com/sql/sql_foreignkey.asp

FOREIGN KEY(...) REFERENCES my_table(...)

CREATE TABLE comments(
	id INT AUTO_INCREMENT PRIMARY KEY,
	comment_text VARCHAR(255) NOT NULL,
	user_id INT NOT NULL,
	photo_id INT NOT NULL,
	created_at TIMESTAMP DEFAULT NOW(),
	FOREIGN KEY(user_id) REFERENCES users(id), -- 👈 Relation
	FOREIGN KEY(photo_id) REFERENCES photos(id)
);

Adding CONSTRAINT

ADD CONSTRAINT ... FOREIGN KEY(...) REFERENCES my_table(...)

CREATE TABLE sports(
    sport_id INT,
    sport_name VARCHAR(255) NOT NULL,
    PRIMARY KEY(sport_id)
);

CREATE TABLE person(
    person_id INT,
    PRIMARY KEY(person_id),
);

ALTER TABLE person
    ADD CONSTRAINT fk_sport_id
    FOREIGN KEY(sport_id) REFERENCES sports(sport_id); -- 👈 Relation

---

SQL+DDL in the same query

Using DDL for schema and identify relationship from SQL JOINs:

FROM a INNER JOIN b ON a.id = b.id

SELECT *
FROM my_table
INNER JOIN another_table ON my_table.id = another_table.id; -- 👈 Relation

-- DDLs
CREATE TABLE my_table (
  id INT,
  name VARCHAR(255)
);

CREATE TABLE another_table (
  id INT,
  description TEXT
);

-- Using REFERENCES
CREATE TABLE new_table (
  id INT UNIQUE PRIMARY KEY,
  another_id INT NOT NULL,
  FOREIGN KEY (another_id) REFERENCES another_table(id), -- 👈 Relation
);