Olá 
Aqui está meu erd e abaixo meus códigos de tabela de criação;
-- Este script foi gerado pela ferramenta ERD no pgAdmin 4. -- Registre um problema em https://redmine.postgresql.org/projects/pgadmin4/issues/new se encontrar algum bug, incluindo etapas de reprodução.
BEGIN;
CREATE TABLE IF NOT EXISTS project1."Posts"
(
post_id serial NOT NULL,
user_id integer NOT NULL,
title "char" NOT NULL,
content text NOT NULL,
created_at timestamp with time zone NOT NULL,
PRIMARY KEY (post_id)
);
CREATE TABLE IF NOT EXISTS project1."Comments"
(
comment_id serial NOT NULL,
"post_id " integer NOT NULL,
"user_id " integer NOT NULL,
"text " text NOT NULL,
"created_at " timestamp with time zone NOT NULL,
PRIMARY KEY (comment_id)
);
CREATE TABLE IF NOT EXISTS project1.users
(
user_id serial NOT NULL,
username "char" NOT NULL,
password "char" NOT NULL,
email "char" NOT NULL,
PRIMARY KEY (user_id)
);
CREATE TABLE IF NOT EXISTS project1.products
(
"product_id " serial NOT NULL,
name "char" NOT NULL,
price numeric NOT NULL,
"category_id " integer NOT NULL,
PRIMARY KEY ("product_id ")
);
CREATE TABLE IF NOT EXISTS project1.orders
(
"order_id " serial NOT NULL,
user_id integer NOT NULL,
"order_date " date NOT NULL,
"total_amount " numeric NOT NULL,
PRIMARY KEY ("order_id ")
);
CREATE TABLE IF NOT EXISTS project1."order_items "
(
item_id serial NOT NULL,
order_id integer NOT NULL,
product_id integer NOT NULL,
quantity integer NOT NULL,
PRIMARY KEY (item_id)
);
CREATE TABLE IF NOT EXISTS project1.invoices
(
invoice_id serial NOT NULL,
order_id integer NOT NULL,
issued_date date NOT NULL,
amount_due numeric NOT NULL,
PRIMARY KEY (invoice_id)
);
CREATE TABLE IF NOT EXISTS project1.reviews
(
review_id serial NOT NULL,
product_id integer NOT NULL,
user_id integer NOT NULL,
rating integer,
comment text NOT NULL,
created_at timestamp with time zone NOT NULL,
PRIMARY KEY (review_id)
);
ALTER TABLE IF EXISTS project1."Posts"
ADD FOREIGN KEY (user_id)
REFERENCES project1.users (user_id) MATCH SIMPLE
ON UPDATE NO ACTION
ON DELETE NO ACTION
NOT VALID;
ALTER TABLE IF EXISTS project1."Comments"
ADD FOREIGN KEY ("post_id ")
REFERENCES project1."Posts" (post_id) MATCH SIMPLE
ON UPDATE NO ACTION
ON DELETE NO ACTION
NOT VALID;
ALTER TABLE IF EXISTS project1."Comments"
ADD FOREIGN KEY ("user_id ")
REFERENCES project1.users (user_id) MATCH SIMPLE
ON UPDATE NO ACTION
ON DELETE NO ACTION
NOT VALID;
ALTER TABLE IF EXISTS project1.orders
ADD FOREIGN KEY (user_id)
REFERENCES project1.users (user_id) MATCH SIMPLE
ON UPDATE NO ACTION
ON DELETE NO ACTION
NOT VALID;
ALTER TABLE IF EXISTS project1."order_items "
ADD FOREIGN KEY (order_id)
REFERENCES project1.orders ("order_id ") MATCH SIMPLE
ON UPDATE NO ACTION
ON DELETE NO ACTION
NOT VALID;
ALTER TABLE IF EXISTS project1.invoices
ADD FOREIGN KEY (order_id)
REFERENCES project1.orders ("order_id ") MATCH SIMPLE
ON UPDATE NO ACTION
ON DELETE NO ACTION
NOT VALID;
ALTER TABLE IF EXISTS project1.reviews
ADD FOREIGN KEY (product_id)
REFERENCES project1.products ("product_id ") MATCH SIMPLE
ON UPDATE NO ACTION
ON DELETE NO ACTION
NOT VALID;
ALTER TABLE IF EXISTS project1.reviews
ADD FOREIGN KEY (user_id)
REFERENCES project1.users (user_id) MATCH SIMPLE
ON UPDATE NO ACTION
ON DELETE NO ACTION
NOT VALID;
END;
Quando estou tentando inserir esses dados;
-- Dados fictícios para project1.users
INSERT INTO project1.users (username, password, email)
VALUES
('user1', 'pass123', '[email protected]'),
('user2', 'pass456', '[email protected]'),
('user3', 'pass789', '[email protected]'),
('user4', 'pass101', '[email protected]'),
('user5', 'pass202', '[email protected]');
-- Dados fictícios para o projeto1."Postagens"
INSERT INTO project1."Posts" (user_id, title, content, created_at)
VALUES
(1, 'Post Title 1', 'Content of post 1', NOW()),
(2, 'Post Title 2', 'Content of post 2', NOW()),
(3, 'Post Title 3', 'Content of post 3', NOW()),
(4, 'Post Title 4', 'Content of post 4', NOW()),
(5, 'Post Title 5', 'Content of post 5', NOW());
-- Dados fictícios para o projeto1."Comentários"
INSERT INTO project1."Comments" ("post_id ", "user_id ", "text ", "created_at ")
VALUES
(1, 2, 'Comment 1 on Post 1', NOW()),
(2, 3, 'Comment 2 on Post 2', NOW()),
(3, 4, 'Comment 3 on Post 3', NOW()),
(4, 5, 'Comment 4 on Post 4', NOW()),
(5, 1, 'Comment 5 on Post 5', NOW());
-- Dados fictícios para project1.products
INSERT INTO project1.products ("product_id ", "name ", "price", "category_id ")
VALUES
(1, 'Product 1', 10.99, 1),
(2, 'Product 2', 20.99, 2),
(3, 'Product 3', 15.99, 1),
(4, 'Product 4', 25.99, 2),
(5, 'Product 5', 12.99, 1);
-- Dados fictícios para project1.orders
INSERT INTO project1.orders ("user_id ", "order_date ", "total_amount ")
VALUES
(1, '2024-01-02', 50.99),
(2, '2024-01-03', 30.99),
(3, '2024-01-04', 45.99),
(4, '2024-01-05', 35.99),
(5, '2024-01-06', 22.99);
-- Dados fictícios para projeto1."order_items " Sql``` INSERT INTO project1."order_items " (order_id, product_id, quantidade) VALUES (1, 1, 2), (2, 3, 1), (3, 5, 3), (4, 2, 2), (5, 4, 1);
-- Dummy data for project1.invoices
```sql
INSERT INTO project1.invoices (order_id, issued_date, amount_due)
VALUES
(1, '2024-01-03', 50.99),
(2, '2024-01-04', 30.99),
(3, '2024-01-05', 45.99),
(4, '2024-01-06', 35.99),
(5, '2024-01-07', 22.99);
-- Dados fictícios para project1.reviews
INSERT INTO project1.reviews (product_id, user_id, rating, comment, created_at)
VALUES
(1, 2, 4, 'Good product', NOW()),
(2, 3, 5, 'Excellent product', NOW()),
(3, 4, 3, 'Average product', NOW()),
(4, 5, 4, 'Very good product', NOW()),
(5, 1, 5, 'Outstanding product', NOW());
Eu continuo recebendo esse erro;
ERRO: A chave (user_id)=(1) não está presente na tabela "users".inserir ou atualizar na tabela "Postagens" viola a restrição de chave estrangeira "Posts_user_id_fkey"
ERRO: inserção ou atualização na tabela "Postagens" viola a restrição de chave estrangeira "Posts_user_id_fkey" Estado SQL: 23503 Detalhe: Chave (user_id)=(1) não está presente na tabela "usuários".
Se alguém puder me ajudar com isso, ficarei feliz. Só quero lembrar que sou novo no SQL e obrigado pelo seu tempo!