Which one is executed first, group by or order by?

The execution order of GROUP BY and ORDER BY clauses in SQL queries is: 1. GROUP BY first groups by the specified grouping column and calculates the aggregate value; 2. ORDER BY then sorts the grouped data according to the sorting column. .

In a SQL query, the execution order of the GROUP BY and ORDER BY clauses is as follows:

1. GROUP BY First execute the

GROUP BY clause to group the data set by the specified grouping column Groups, and calculates the aggregate value for each group (e.g., sums, averages).

2. ORDER BY Then execute the

##ORDER BY clause to group the data set Sort by the specified sort column.

Example:

<code class="sql">SELECT SUM(sales)
FROM sales_data
GROUP BY product_id
ORDER BY product_id;</code>

In this example:

1. GROUP BY product_id Group the data set by product_id Groups and calculates the total sales for each group.
2. ORDER BY product_id Sort the grouped data set in ascending order by product_id.

So the end result will be a set of grouped data, sorted by

product_id in ascending order.

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