#посмотреть
▫️Что такое оконные функции SQL
▫️Зачем нужны
▫️Примеры использования
▫️Синтаксис
▫️Разница оконных функций и GROUP BY
▫️Классы оконных функций
▫️SUM
▫️AVG
▫️COUNT
▫️MIN / MAX
▫️ROW_NUMBER
▫️RANK
▫️DENSE_RANK
▫️NTILE
▫️LAG
▫️LEAD
▫️FIRST_VALUE / LAST_VALUE
▫️NTH_VALUE
или
BY SQL для тестировщика
Bitcoin is built on a distributed digital record called a blockchain. As the name implies, blockchain is a linked body of data, made up of units called blocks that contain information about each and every transaction, including date and time, total value, buyer and seller, and a unique identifying code for each exchange. Entries are strung together in chronological order, creating a digital chain of blocks. “Once a block is added to the blockchain, it becomes accessible to anyone who wishes to view it, acting as a public ledger of cryptocurrency transactions,” says Stacey Harris, consultant for Pelicoin, a network of cryptocurrency ATMs. Blockchain is decentralized, which means it’s not controlled by any one organization. “It’s like a Google Doc that anyone can work on,” says Buchi Okoro, CEO and co-founder of African cryptocurrency exchange Quidax. “Nobody owns it, but anyone who has a link can contribute to it. And as different people update it, your copy also gets updated.”
SQL для тестировщика from in