Solution 1

CREATE TABLE deposit_types(
deposit_type_id INT PRIMARY KEY UNIQUE AUTO_INCREMENT,
name VARCHAR(20)
);

CREATE TABLE deposits(
deposit_id INT PRIMARY KEY AUTO_INCREMENT,
amount DECIMAL(10,2),
start_date DATE,
end_date DATE,
deposit_type_id INT,
customer_id INT,
CONSTRAINT fk_deposits_deposit_types
FOREIGN KEY(deposit_type_id)
REFERENCES deposit_types(deposit_type_id),

CONSTRAINT fk_deposits_customers
FOREIGN KEY(customer_id)
REFERENCES customers(customer_id)
);


CREATE TABLE credit_history
(
credit_history_id INT PRIMARY KEY,
mark CHAR(1),
start_date DATE,
end_date DATE,
customer_id INT,

CONSTRAINT fk_credit_history_customers
FOREIGN KEY(customer_id)
REFERENCES customers(customer_id)
);

CREATE TABLE payments
(
payement_id INT PRIMARY KEY,
`date` DATE,
amount DECIMAL(10,2),
loan_id INT,

CONSTRAINT fk_payments_loans
FOREIGN KEY(loan_id)
REFERENCES loans(loan_id)
);

CREATE TABLE users
(
user_id INT PRIMARY KEY,
user_name VARCHAR(20),
`password` VARCHAR(20),
customer_id INT UNIQUE,

CONSTRAINT fk_users_customers
FOREIGN KEY(customer_id)
REFERENCES customers(customer_id)
);

ALTER TABLE employees
ADD manager_id INT,
ADD CONSTRAINT fk_employees_employees
FOREIGN KEY(manager_id)
REFERENCES employees(employee_id)
;