SQL Union
UNION is an operator that concatenates results of different SQL queries:
1234567--do not run this query SELECT columns FROM table1 UNION SELECT columns FROM table2 UNION ... SELECT columns FROM tableN
There is also an operator UNION ALL, and the difference is that UNION returns distinct values, unlike UNION ALL.
Requirements for using UNION operators:
- number of columns in
SELECTshould be the same - data types and order of columns should be the same
Swipe to start coding
You want to get some info about songs from three decades: 1970s, 1980s, and 1990s. Find the prices of the cheapest and the most expensive songs for each decade in separate queries. You're free to use JOIN, BETWEEN, or any other operators, but you should do three separate queries and concatenate them with UNION.
Solution
Merci pour vos commentaires !
single
Demandez à l'IA
Demandez à l'IA
Posez n'importe quelle question ou essayez l'une des questions suggérées pour commencer notre discussion
Awesome!
Completion rate improved to 5.88SQL Union
Glissez pour afficher le menu
UNION is an operator that concatenates results of different SQL queries:
1234567--do not run this query SELECT columns FROM table1 UNION SELECT columns FROM table2 UNION ... SELECT columns FROM tableN
There is also an operator UNION ALL, and the difference is that UNION returns distinct values, unlike UNION ALL.
Requirements for using UNION operators:
- number of columns in
SELECTshould be the same - data types and order of columns should be the same
Swipe to start coding
You want to get some info about songs from three decades: 1970s, 1980s, and 1990s. Find the prices of the cheapest and the most expensive songs for each decade in separate queries. You're free to use JOIN, BETWEEN, or any other operators, but you should do three separate queries and concatenate them with UNION.
Solution
Passez à un bureau pour une pratique réelleContinuez d'où vous êtes en utilisant l'une des options ci-dessousMerci pour vos commentaires !
Awesome!
Completion rate improved to 5.88single
