ROLLUP
Group by (a,b,c) with rollup；
represents the given list of expressions and all their prefixes (including the empty list), equivalent to:
Group by (a,b,c) union all
Group by (a,b) union all
Group by (a) union all
Group by ()；
CUBE
Group by (a,b,c) with cube；
represents all combinations of the given expression list, equivalent to:
Group by (a,b,c) union all
Group by (a,b) union all
Group by (a,c) union all
Group by (b,c) union all
Group by (a) union all
Group by (b) union all
Group by (c) union all
Group by ();
GROUPING SETS
Group by grouping sets((a,b),(b,c),());
represents a grouping of the given list of expressions, equivalent to:
Group by (a,b) union all
Group by (b,c) union all
Group by ();
Features
Design a table with the following format:
Insert the following data into the table
We can use the following statement to group and query the total revenue:
select year,country,product,sum(profit)
from sales
group by year,country,product;
When we want to know the sub-level of a certain level, such as the income of all products in a certain country in a certain year, we can use ROLL UP
select year,country,product,sum(profit)
from sales
group by year,country,product with rollup;
But ROLL UP only shows a certain level of the selected column. When we want to know all the combinations of the selected columns, we can use CUBE
select year,country,product,sum(profit)
from sales
group by year,country,product with cube;
Sometimes we also need to choose the columns we want to query by ourselves. At this time, we can use grouping sets
select year,country, product,sum(profit)
from sales
group by grouping sets ((year,country),(year,product),());
