UNION та EXCEPT

Published: 25 January 2023
on channel: spa it

119

UNION
EXCEPT
та ще раз INNER JOIN

UNION поєднує результат із кількох блоків запиту в єдиний набір результатів.
EXCEPT обмежує результат з першого блоку запиту тими рядками, які не знайдені в другому.

DROP DATABASE base2;
CREATE DATABASE base2;

USE base2;
CREATE TABLE Customers
(
Id INT PRIMARY KEY AUTO_INCREMENT,
Age INT,
FirstName VARCHAR(20) NOT NULL,
LastName VARCHAR(20) NOT NULL,
Phone VARCHAR(20)
);

CREATE TABLE CHobby
(
Id INT PRIMARY KEY AUTO_INCREMENT,
Age INT,
FirstName VARCHAR(20) NOT NULL,
LastName VARCHAR(20) NOT NULL,
Hobby VARCHAR(20)
);

INSERT Customers(Age, FirstName, LastName, Phone)
VALUES (18,'Ganna','Velickiv','0688889977');
INSERT Customers(Age, FirstName, LastName, Phone)
VALUES (19,'Ury','Medvejuy','0688889988');
INSERT Customers(Age, FirstName, LastName, Phone)
VALUES (39,'Anton','Chernov','0687889988');

INSERT CHobby(Age, FirstName, LastName, Hobby)
VALUES (18,'Ganna','Velickiv','alcohol');

SELECT FirstName, LastName
FROM Customers
UNION SELECT FirstName, LastName FROM CHobby;

SELECT FirstName, LastName
FROM Customers
EXCEPT SELECT FirstName, LastName FROM CHobby;

SELECT Customers.Id, Customers.FirstName, Customers.LastName
FROM Customers
INNER JOIN CHobby ON CHobby.FirstName=Customers.FirstName AND CHobby.LastName=Customers.LastName;

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