SQL Group By

GROUP BY is an operator that puts rows with the same values of the field in groups. It creates one row for each group, so it makes sense to use some aggregate function in SELECT. For example, let's group our songs by singers, and find a number of songs for each singer:


              123
            
SELECT COUNT(Id), singer
FROM songs
GROUP BY singer

This query will return a list of singers, as well as, for each of them, the number of songs. Each singer represents a unit or group, and COUNT() aggregate function is applied for records in the group. You can use GROUP BY with ORDER BY, and also group by multiple columns. Here is a syntax of query:


              123456
            
-- do not run this query
SELECT col1, col2, ...
FROM table
WHERE condition
GROUP BY col1, col2, ...
ORDER BY col1, col2, ...;

Завдання

For each singer, create groups with info about singer and price of the most expensive song. Order these groups by singer.

Перейдіть на комп'ютер для реальної практикиПродовжуйте з того місця, де ви зупинились, використовуючи один з наведених нижче варіантів

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Дякуємо за ваш відгук!

Секція 3. Розділ 7

SQL Group By


              123
            
SELECT COUNT(Id), singer
FROM songs
GROUP BY singer


              123456
            
-- do not run this query
SELECT col1, col2, ...
FROM table
WHERE condition
GROUP BY col1, col2, ...
ORDER BY col1, col2, ...;

Завдання

For each singer, create groups with info about singer and price of the most expensive song. Order these groups by singer.

Все було зрозуміло?

Дякуємо за ваш відгук!

Секція 3. Розділ 7

SQL Group By


              123
            
SELECT COUNT(Id), singer
FROM songs
GROUP BY singer


              123456
            
-- do not run this query
SELECT col1, col2, ...
FROM table
WHERE condition
GROUP BY col1, col2, ...
ORDER BY col1, col2, ...;

Завдання

For each singer, create groups with info about singer and price of the most expensive song. Order these groups by singer.

Все було зрозуміло?

Дякуємо за ваш відгук!


              123
            
SELECT COUNT(Id), singer
FROM songs
GROUP BY singer


              123456
            
-- do not run this query
SELECT col1, col2, ...
FROM table
WHERE condition
GROUP BY col1, col2, ...
ORDER BY col1, col2, ...;

Завдання

For each singer, create groups with info about singer and price of the most expensive song. Order these groups by singer.

Секція 3. Розділ 7