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5. Aggregations

Attention

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YCQL

YugabyteDB supports a number of standard aggregation functions. Let us go through some of these using an example. Consider a products table as shown below.

ProductID	ProductName	SupplierID	CategoryID	Unit	Price	Quantity
1	Chais	1	1	10 boxes x 20 bags	18	25
2	Chang	1	1	24 - 12 oz bottles	19	12
3	Aniseed Syrup	1	2	12 - 550 ml bottles	10	10
4	Chef Anton's Cajun Seasoning	2	2	48 - 6 oz jars	22	9
5	Chef Anton's Gumbo Mix	2	2	36 boxes	21.35	40

Let us create this table with ProductID as the primary hash key.

cqlsh> CREATE KEYSPACE store;

cqlsh> CREATE TABLE store.products (ProductID BIGINT PRIMARY KEY, ProductName VARCHAR, SupplierID INT, CategoryID INT, Unit TEXT, Price FLOAT, Quantity INT);

Now let us populate the sample data.

INSERT INTO store.products (ProductID, ProductName, SupplierID, CategoryID, Unit, Price, Quantity) VALUES (1, 'Chais', 1, 1, '10 boxes x 20 bags', 18, 25);
INSERT INTO store.products (ProductID, ProductName, SupplierID, CategoryID, Unit, Price, Quantity) VALUES (2, 'Chang', 1, 1, '24 - 12 oz bottles', 19, 12);
INSERT INTO store.products (ProductID, ProductName, SupplierID, CategoryID, Unit, Price, Quantity) VALUES (3, 'Aniseed Syrup', 1, 2, '12 - 550 ml bottles', 10, 10);
INSERT INTO store.products (ProductID, ProductName, SupplierID, CategoryID, Unit, Price, Quantity) VALUES (4, 'Chef Anton''s Cajun Seasoning', 2, 2, '48 - 6 oz jars', 22, 9);
INSERT INTO store.products (ProductID, ProductName, SupplierID, CategoryID, Unit, Price, Quantity) VALUES (5, 'Chef Anton''s Gumbo Mix', 2, 2, '36 boxes', 21.35, 40);

Counts

Finding the number of item types in the store can be done as follows.

cqlsh> SELECT COUNT(ProductID) FROM store.products;

 count(productid)
------------------
                5
(1 rows)

We can give an alias name to the count column as follows.

cqlsh> SELECT COUNT(ProductID) as num_products FROM store.products;

 num_products
--------------
            5
(1 rows)

Finding the number of item types for supplier 1 can be done as follows.

You can do this as shown below.

cqlsh> SELECT COUNT(ProductID) as supplier1_num_products FROM store.products WHERE SupplierID=1;

supplier1_num_products ------------------------ 3

(1 rows)

Numeric aggregation functions

The standard aggregate functions of min, max, sum, avg and count are built-in functions.

To find the total number of items in the store, run the following query.

cqlsh> SELECT SUM(Quantity) FROM store.products;

 sum(quantity)
---------------
            96
(1 rows)

To find the price of the cheapest and the most expensive item, run the following.

cqlsh> SELECT MIN(Price), MAX(Price) FROM store.products;

 min(price) | max(price)
------------+------------
         10 |         22
(1 rows)

To find the average price of all the items in the store, run the following.

cqlsh> SELECT AVG(price) FROM store.products;

 system.avg(price)
-------------------
             18.07
(1 rows)