Note: If you do not have a database, as well as an application to support the practicum, then don't worry, some of these tools are not big, please download them here:
In returning the value of data, several query calculations are required, which are expressed by aggregate functions in the form of SQL commands, including the following:
1. COUNT
The COUNT command is used to count the number of data in a table.
Below is an example of using the COUNT command to count the number of data in the employees table (don't forget to install the Northwind database first).
SELECT COUNT(*) FROM employees;
Executing the COUNT Command
2. SUM
Used to return the total value of a specified column.
Now we will try to use the SUM command to calculate the total products that are still available.
SELECT SUM(UnitsInStock) FROM products;
Execute SUM Command
3. AVG
Used to return the average value of a specified column.
For example, we will try to find out about the average number of products ordered by most customers.
SELECT AVG(Quantity) FROM order_details;
AVG Command Execution
As per the results above, we can conclude that the average number of products ordered by customers ranges from 23 to 24 units.
4. MIN
The MIN command is used to return the smallest value from a specified column.
For example, let's use the command to find out the least stock of a product.
SELECT ProductName, UnitsInStock FROM products
WHERE UnitsInStock =
(
SELECT MIN(UnitsInStock) FROM products
);
MIN Command Execution
5. MAX
The MAX command is used to return the largest value from a specified column.
Still the same, regarding product stock, now we try to use the command to find the product with the most stock.
SELECT ProductName, UnitsInStock FROM products
WHERE UnitsInStock =
(
SELECT MAX(UnitsInStock) FROM products
);
MAX Command Execution
6. Additional Notes
1. MAX
Used to display the largest record value in a field.
Example:
Select max(saldo) as 'Saldo Tertinggi' from rekening
To use aggregate functions simultaneously, you can use a comma ( , )
Example:
Select max(saldo) as 'Saldo Tertinggi', min(saldo) as 'Saldo Terendah', avg(Saldo) as 'Saldo Rata-rata', count(saldo) as 'Jumlah' from rekening
MAX is part of the SQL aggregate functions, along with other functions such as SUM, AVG, COUNT and MIN.
2. MIN
Used to display the smallest record value in a field.
Example:
Select min(saldo) as 'Saldo Terendah' from rekening
Example:
Select max(saldo) as 'Saldo Tertinggi', min(saldo) as 'Saldo Terendah', avg(Saldo) as 'Saldo Rata-rata', count(saldo) as 'Jumlah' from rekening
MIN is part of the SQL aggregate functions, along with other functions such as SUM, AVG, COUNT and MAX.
3. COUNT
Used to count the number of records in a table.
Example:
Select count(*) as 'Jumlah Record' from nasabah
Example:
Select max(saldo) as 'Saldo Tertinggi', min(saldo) as 'Saldo Terendah', avg(Saldo) as 'Saldo Rata-rata', count(saldo) as 'Jumlah' from rekening
COUNT is part of the SQL aggregate functions, along with other functions such as SUM, AVG, MIN and MAX.
4. AVG
Used to find the average value of records in one field.
Example:
Select avg(saldo),min(saldo) from rekening
Example:
Select max(saldo) as 'Saldo Tertinggi', min(saldo) as 'Saldo Terendah', avg(Saldo) as 'Saldo Rata-rata', count(saldo) as 'Jumlah' from rekening
AVG is part of the SQL aggregate functions, along with other functions such as SUM, COUNT, MIN and MAX.
5. SUM
Used to add up the record values in a field. This function can only be used on integer/numeric data.
Example:
Select sum(saldo) as 'Total Saldo' from rekening
SUM is part of the SQL aggregate functions, along with other functions such as AVG, COUNT, MIN and MAX.