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deleted old homework

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Alex
2026-02-13 16:10:48 +03:00
parent 0bdc2ef452
commit df8159a287
6 changed files with 0 additions and 232 deletions
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aharlamcev/postgresql/BaseSQLhomework.sql
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select * from users
select id, name, country from users
order by name;
select id, name, country, created_at from users
where country = 'KZ'
order by created_at desc;
select id, name from users
where email is null;
select id, name from users
where email is not null;
update users
set email = 'alice@mail.com'
where name = 'Alice'; -- в моей таблице ни у кого нет email, добавил чтобы посмотреть.
select id, name, UPPER(email) as email_upper from users;
select id, name, LOWER(email) as email_lower from users
where email is not null;
select id, name, created_at from users
where created_at > '2024-01-11'
order by created_at desc
limit 2;
aharlamcev/postgresql/DMLhomework.sql
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select * from users
insert into users (id, name, email, country, created_at)
values (1, 'Alice', null, 'KZ', '2026-01-17');
insert into users (id, name, email, country, created_at)
values (2, 'Bob', null, 'USA', '2026-01-17');
insert into users (id, name, email, country, created_at)
values (3, 'Charlie', null, 'RU', '2026-01-17');
select * from products
insert into products (id, name, category, price, in_stock)
values (1, 'Mi Band 7', 'smartwatch', 49, true)
insert into products (id, name, category, price, in_stock)
values (2, 'Surface Pro', 'tablet', 1299, true)
insert into products (id, name, category, price, in_stock)
values (3, 'Iphone 15', 'smartphone', 999, true)
insert into products (id, name, category, price, in_stock)
values (4, 'Logitech MX Master', 'mouse', 120, true)
insert into orders (id, user_id, order_date, status)
values (1, 1, '2026-01-17', 'in delivery');
insert into orders (id, user_id, order_date, status)
values (2, 1, '2026-01-17', 'shipped');
insert into orders (id, user_id, order_date, status)
values (3, 2, '2026-01-17', 'preparing');
select * from order_items
insert into order_items (order_id, product_id, quantity, price_at_purchase)
values (1,1, 2, 49)
insert into order_items (order_id, product_id, quantity, price_at_purchase)
values (1, 2, 1, 1299)
insert into order_items (order_id, product_id, quantity, price_at_purchase)
values (2, 3, 1, 999)
insert into order_items (order_id, product_id, quantity, price_at_purchase)
values (3, 4, 2, 120)
insert into order_items (order_id, product_id, quantity, price_at_purchase)
values (3, 1, 2, 49)
-- Сейчас уже понял, что можно после insert - values добавлять сразу в скобках несколько штук, но изначально делал так.
aharlamcev/postgresql/Filtrationhomework.sql
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select * from products
select name, category, price, price * 1.3 as price_with_markup, price * 1.5 as price_with_vat
from products
where in_stock is true and category != 'smartwatch' and price between 100 and 1300;
select name, price, price * 0.85 as price_with_discount
from products
where price < 100 or price > 1000;
select id, name, category, price from products
where category in ('tablet', 'smartphone', 'mouse') and price > 100;
select name, category, price from products
where name not ilike '%iphone%';
select name, category, price from products
where name ilike '%pro%';
select name, category, price from products
where name ilike '%mx%'
order by price desc;
aharlamcev/postgresql/WindowFunctionHomework.sql
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create table products_extended (
id INT primary key,
name VARCHAR(50) not null,
category VARCHAR(50) not null,
price INT,
in_stock BOOLEAN default true,
email_support VARCHAR(50)
);
insert into products_extended (id, name, category, price, in_stock, email_support)
values (1, 'iPhone 14', 'smartphone', 799, true, 'iphone@apple.com'),
(2, 'MacBook Air', 'laptop', 1199, false, NULL),
(3, 'Galaxy S22', 'smartphone', 699, true, 'galaxy@support.com'),
(4, 'ThinkPad X1', 'laptop', 1399, true, 'thinkpad@lenovo.com'),
(5, 'iPad Pro', 'tablet', 999, false, 'ipad@apple.com'),
(6, 'Kindle Paperwhite', 'ebook_reader', 149, true, NULL),
(7, 'Mi Band 7', 'smartwatch', 49, true, 'miband@xiaomi.com'),
(8, 'Surface Pro', 'tablet', 1299, true, 'surface@microsoft.com'),
(9, 'Honor Pad X9', 'tablet', 219, true, 'honor@support.com'),
(10, 'Dell XPS 13', 'laptop', 1099, false, 'dell@support.com');
alter table products_extended
alter column price type DECIMAL(10, 2)
------------------ Задание №1 (По нему ты говорил, что нечитаемо, объясни как переделать pls <3)
with email_false as (select * from
(
select category, name, price, email_support,
row_number() over (partition by category order by price desc) as rn
from products_extended
where email_support is null)
where rn = 1
),
email_true as (select * from
(
select category, name, price, email_support,
row_number() over (partition by category order by price desc) as rn
from products_extended
where email_support is not null)
where rn = 1
)
select category, name, price, email_support from email_false
union all
select category, name, price, email_support from email_true
order by category, price desc
---------------------- Задание №2 (Переделал с двух оконок в одном запросе на СТЕ с одной оконкой внутри)
with get_data as (
select name, category, price,
LEAD(price) OVER (PARTITION BY category order by price) AS next_price
from products_extended
)
select name, category, price, next_price,
price - next_price AS diff
from get_data
--------------------- Задание №3
select category, name, price,
SUM(price) over (partition by category order by price) as cumulative_sales
from products_extended
---------------------- Задание №4
with get_data as (
select category, name, price, AVG(price) over (partition by category) as avg_price
from products_extended
)
select category, name, price, avg_price,
case when price > avg_price then true else false end as is_above_avg
from get_data
aharlamcev/postgresql/homeworkDDL.sql
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create table users (
id int primary key,
name VARCHAR(100) not null,
email VARCHAR(100),
country VARCHAR(50),
crated_at date not null
) ;
create table products (
id int primary key,
name VARCHAR(100) not null,
category VARCHAR(50),
price DECIMAL(10, 2),
in_stock BOOLEAN default true
) ;
create table orders (
id int primary key,
user_id int,
order_date DATE not null,
status VARCHAR(20),
foreign key (user_id) references users(id)
) ;
create table order_items (
order_id int,
product_id int,
quantity int not null,
price_at_purchase DECIMAL(10, 2) not null,
foreign key (order_id) references orders(id),
foreign key (product_id) references products(id)
) ;
alter table users
rename column crated_at to created_at;
aharlamcev/postgresql/sqlhomework.sql
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create table products_extended (
id INT primary key,
name VARCHAR(100) not null,
category VARCHAR(50),
price DECIMAL(10, 2),
in_stock BOOLEAN default true,
email_support VARCHAR(50)
);
insert into products_extended (id, name, category, price, in_stock, email_support)
values (1, 'Mi Band 7', 'smartwatch', 49, true, 'miband@xiaomi.com');
insert into products_extended (id, name, category, price, in_stock, email_support)
values (2, 'Surface Pro', 'tablet', 1299, true, 'surface@microsoft.com');
select * from products_extended -- проверил как выглядит таблица
alter table products_extended
add column rating DECIMAL(5, 2);
truncate table products_extended;
drop table products_extended