How to convert an ER Diagram to SQL using StackRender

How to go from ERD to SQL

Designing a database visually on a digital canvas or whiteboard is satisfying. You map out your entities, draw primary and foreign key relationships, and carefully structure your columns.

But then comes the tedious part: translating that visual model into raw, production-ready code.

Manually converting an ER diagram to SQL is time-consuming, repetitive, and notoriously error-prone. One missed comma, a misplaced foreign key constraint, or a typo in a data type can easily break your migration script when you run it against your database engine.

The bridge between visual design and database execution shouldn't feel like manual labor. In this guide, we’ll look at how to convert an ERD to SQL automatically using our database schema design tool taking your design from a visual blueprint to clean, dialect-specific SQL DDL in just a few clicks.

Export SQL from StackRender

To export the generated SQL from your diagram:

Navigate to the top menu bar and select File → Export SQL.
The Export SQL modal will pop up. Inspect the auto-generated DDL script to verify your table structures, primary keys, foreign key constraints, and indexes.
Click Copy to copy the script directly to your clipboard, or download the .sql file, and execute it in your target database client or migration pipeline.

Safe Execution: StackRender automatically wraps your generated DDL script in BEGIN; and COMMIT; transaction statements. This ensures atomic execution—if any statement fails during execution, the entire script rolls back safely, keeping your database state clean.

Example: Generated SQL DDL Output

To give you an idea of what StackRender produces, here is an example of an auto-generated PostgreSQL script for a complete hospital management schema. Notice how custom ENUM types, table definitions, secondary indexes, and foreign key constraints are cleanly isolated and structured for error-free deployment:

BEGIN;

CREATE TYPE "billing_payment_status_enum" AS ENUM('Pending', 'Paid', 'Partially_Paid', 'Refunded');

CREATE TABLE "billing" (
  bill_id INTEGER NOT NULL PRIMARY KEY,
  patient_id INTEGER NOT NULL,
  admission_id INTEGER NULL,
  total_amount NUMERIC(10, 2) NOT NULL,
  paid_amount NUMERIC(10, 2) NULL DEFAULT 0,
  payment_status billing_payment_status_enum NULL DEFAULT 'Pending',
  issued_date TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP,
  due_date DATE NOT NULL
);

CREATE INDEX "idx_billing_patient" ON "billing" ("patient_id");

CREATE TABLE "prescription_items" (
  prescription_item_id INTEGER NOT NULL PRIMARY KEY,
  prescription_id INTEGER NOT NULL,
  medication_id INTEGER NOT NULL,
  dosage VARCHAR(50) NOT NULL,
  frequency VARCHAR(50) NOT NULL,
  duration_days INTEGER NOT NULL
);

CREATE TABLE "prescriptions" (
  prescription_id INTEGER NOT NULL PRIMARY KEY,
  record_id INTEGER NOT NULL,
  prescribed_date TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP,
  notes TEXT NULL
);

CREATE TABLE "medications" (
  medication_id INTEGER NOT NULL PRIMARY KEY,
  name VARCHAR(100) NOT NULL UNIQUE,
  brand_name VARCHAR(100) NULL,
  unit_cost NUMERIC(8, 2) NOT NULL,
  stock_quantity INTEGER NULL DEFAULT 0
);

CREATE TABLE "medical_records" (
  record_id INTEGER NOT NULL PRIMARY KEY,
  patient_id INTEGER NOT NULL,
  doctor_id INTEGER NOT NULL,
  visit_date TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP,
  symptoms TEXT NULL,
  diagnosis TEXT NOT NULL,
  treatment_plan TEXT NULL
);

CREATE INDEX "idx_medical_records_patient" ON "medical_records" ("patient_id");

CREATE TYPE "appointments_status_enum" AS ENUM('Scheduled', 'Completed', 'Cancelled', 'No-Show');

CREATE TABLE "appointments" (
  appointment_id INTEGER NOT NULL PRIMARY KEY,
  patient_id INTEGER NOT NULL,
  doctor_id INTEGER NOT NULL,
  appointment_date TIMESTAMP NOT NULL,
  status appointments_status_enum NULL DEFAULT 'Scheduled',
  reason_for_visit TEXT NULL,
  created_at TIMESTAMP NULL DEFAULT CURRENT_TIMESTAMP
);

CREATE INDEX "idx_appointments_patient" ON "appointments" ("patient_id");

CREATE INDEX "idx_appointments_doctor" ON "appointments" ("doctor_id");

CREATE TABLE "admissions" (
  admission_id INTEGER NOT NULL PRIMARY KEY,
  patient_id INTEGER NOT NULL,
  room_id INTEGER NOT NULL,
  admission_date TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP,
  discharge_date TIMESTAMP NULL,
  primary_diagnosis TEXT NULL
);

CREATE INDEX "idx_admissions_patient" ON "admissions" ("patient_id");

CREATE TYPE "rooms_status_enum" AS ENUM(
  'Available',
  'Occupied',
  'Maintenance',
  'Reserved'
);

CREATE TABLE "rooms" (
  room_id INTEGER NOT NULL PRIMARY KEY,
  room_number VARCHAR(10) NOT NULL UNIQUE,
  room_type VARCHAR(50) NOT NULL,
  daily_rate NUMERIC(10, 2) NOT NULL,
  status rooms_status_enum NULL DEFAULT 'Available'
);

CREATE TYPE "patients_gender_enum" AS ENUM('Male', 'Female', 'Other');

CREATE TABLE "patients" (
  patient_id INTEGER NOT NULL PRIMARY KEY,
  first_name VARCHAR(50) NOT NULL,
  last_name VARCHAR(50) NOT NULL,
  date_of_birth DATE NOT NULL,
  gender patients_gender_enum NOT NULL,
  phone_number VARCHAR(20) NOT NULL,
  email VARCHAR(100) NULL,
  address TEXT NULL,
  emergency_contact_name VARCHAR(100) NULL,
  emergency_contact_phone VARCHAR(20) NULL,
  created_at TIMESTAMP NULL DEFAULT CURRENT_TIMESTAMP
);

CREATE TABLE "doctors" (
  doctor_id INTEGER NOT NULL PRIMARY KEY,
  first_name VARCHAR(50) NOT NULL,
  last_name VARCHAR(50) NOT NULL,
  specialty VARCHAR(100) NOT NULL,
  license_number VARCHAR(50) NOT NULL UNIQUE,
  phone_number VARCHAR(20) NULL,
  email VARCHAR(100) NULL UNIQUE,
  department_id INTEGER NOT NULL,
  created_at TIMESTAMP NULL DEFAULT CURRENT_TIMESTAMP
);

CREATE INDEX "idx_doctors_department" ON "doctors" ("department_id");

CREATE TABLE "departments" (
  department_id INTEGER NOT NULL PRIMARY KEY,
  department_name VARCHAR(100) NOT NULL UNIQUE,
  building_location VARCHAR(100) NULL,
  phone_number VARCHAR(20) NULL,
  created_at TIMESTAMP NULL DEFAULT CURRENT_TIMESTAMP
);

ALTER TABLE "billing"
ADD CONSTRAINT "fk_billing_patient" FOREIGN KEY (patient_id) REFERENCES "patients" (patient_id) ON DELETE CASCADE;

ALTER TABLE "prescription_items"
ADD CONSTRAINT "fk_item_medication" FOREIGN KEY (medication_id) REFERENCES "medications" (medication_id) ON DELETE RESTRICT;

ALTER TABLE "medical_records"
ADD CONSTRAINT "fk_record_doctor" FOREIGN KEY (doctor_id) REFERENCES "doctors" (doctor_id) ON DELETE RESTRICT;

ALTER TABLE "doctors"
ADD CONSTRAINT "fk_doctor_department" FOREIGN KEY (department_id) REFERENCES "departments" (department_id) ON DELETE RESTRICT;

ALTER TABLE "appointments"
ADD CONSTRAINT "fk_appointment_doctor" FOREIGN KEY (doctor_id) REFERENCES "doctors" (doctor_id) ON DELETE RESTRICT;

ALTER TABLE "billing"
ADD CONSTRAINT "fk_billing_admission" FOREIGN KEY (admission_id) REFERENCES "admissions" (admission_id) ON DELETE SET NULL;

ALTER TABLE "appointments"
ADD CONSTRAINT "fk_appointment_patient" FOREIGN KEY (patient_id) REFERENCES "patients" (patient_id) ON DELETE CASCADE;

ALTER TABLE "prescriptions"
ADD CONSTRAINT "fk_prescription_record" FOREIGN KEY (record_id) REFERENCES "medical_records" (record_id) ON DELETE CASCADE;

ALTER TABLE "medical_records"
ADD CONSTRAINT "fk_record_patient" FOREIGN KEY (patient_id) REFERENCES "patients" (patient_id) ON DELETE CASCADE;

ALTER TABLE "admissions"
ADD CONSTRAINT "fk_admission_patient" FOREIGN KEY (patient_id) REFERENCES "patients" (patient_id) ON DELETE CASCADE;

ALTER TABLE "prescription_items"
ADD CONSTRAINT "fk_item_prescription" FOREIGN KEY (prescription_id) REFERENCES "prescriptions" (prescription_id) ON DELETE CASCADE;

ALTER TABLE "admissions"
ADD CONSTRAINT "fk_admission_room" FOREIGN KEY (room_id) REFERENCES "rooms" (room_id) ON DELETE RESTRICT;

COMMIT;

How to convert an ER Diagram to SQL using StackRender

How to go from ERD to SQL

Export SQL from StackRender

Example: Generated SQL DDL Output

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