Aggregation and ordering operators

ORDER BY

The ORDER BY keyword is used to sort the result-set in ascending or descending order.

The ORDER BY keyword sorts the records in ascending order by default. To sort the records in descending order, use the DESC keyword.

SELECT column1, column2, ... 
FROM table_name 
ORDER BY column1, column2, ... ASC|DESC;

MIN

The MIN() function returns the smallest value of the selected column.

SELECT MIN(column_name)
FROM table_name
WHERE condition;

MAX

The MAX() function returns the largest value of the selected column.

SELECT MAX(column_name)
FROM table_name
WHERE condition;

COUNT

The COUNT() function returns the number of rows that matches a specified criterion.

SELECT COUNT(column_name)
FROM table_name
WHERE condition;

AVG

The AVG() function returns the average value of a numeric column.

SELECT AVG(column_name)
FROM table_name
WHERE condition;

SUM

The SUM() function returns the total sum of a numeric column.

SELECT SUM(column_name)
FROM table_name
WHERE condition;

GROUP BY

The GROUP BY statement groups rows that have the same values into summary rows, like "find the number of customers in each country".

The GROUP BY statement is often used with aggregate functions (COUNT(), MAX(), MIN(), SUM(), AVG()) to group the result-set by one or more columns.

SELECT column_name(s)
FROM table_name
WHERE condition
GROUP BY column_name(s)
ORDER BY column_name(s);

HAVING

The HAVING clause was added to SQL because the WHERE keyword cannot be used with aggregate functions.

SELECT column_name(s)
FROM table_name
WHERE condition
GROUP BY column_name(s)
HAVING condition
ORDER BY column_name(s);

References

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