ORDER BY vs GROUP BY in SQL: Key Differences

Order by and group by are two commonly used keywords in SQL queries, with the main difference between them being as follows:

1. Function difference: order by is used to sort the query result, while group by is used to group the query result based on fields.
2. Different targets: order by affects all rows in the query result set, used for sorting the result set; while group by affects the grouping fields in the query result set, used for grouping the result set by these fields.
3. The results differ: ‘order by’ sorts the entire result set without merging or deduplicating, so there may be duplicate rows; whereas ‘group by’ groups the result set based on grouping fields, merging and deduplicating each group, ensuring no duplicate rows in the result set.
4. Usage differs: the “order by” clause is typically used in conjunction with a select statement to sort the query results, whereas the “group by” clause is typically used with aggregate functions to group and calculate aggregates in query results.

In general, order by is used to sort the result set, while group by is used to group the result set.