Write a SQL query for: Display customers that have neither loan nor account. cre

Question

Write a SQL query for:

Display customers that have neither loan nor account.

create table account

(account_number varchar(15) not null,

branch_name varchar(15) not null,

balance number not null,

primary key(account_number));

create table branch

(branch_name varchar(15) not null,

branch_city varchar(15) not null,

assets number not null,

primary key(branch_name));

create table customer

(customer_name varchar(15) not null,

customer_street varchar(12) not null,

customer_city varchar(15) not null,

primary key(customer_name));

create table loan

(loan_number varchar(15) not null,

branch_name varchar(15) not null,

amount number not null,

primary key(loan_number));

create table depositor

(customer_name varchar(15) not null,

account_number varchar(15) not null,

primary key(customer_name, account_number),

foreign key(account_number) references account(account_number),

foreign key(customer_name) references customer(customer_name));

create table borrower

(customer_name varchar(15) not null,

loan_number varchar(15) not null,

primary key(customer_name, loan_number),

foreign key(customer_name) references customer(customer_name),

foreign key(loan_number) references loan(loan_number));

Explanation / Answer

SELECT customer_name FROM customer c WHERE NOT EXISTS ( SELECT 1 -- mostly irrelevant whatever you put here FROM borrower b WHERE c.customer_name = b.customer_name ) AND NOT EXISTS ( SELECT 1 -- mostly irrelevant whatever you put here FROM depositor d WHERE c.customer_name = d.customer_name ) ;

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