What does order by mean in mysql?

The ORDER BY clause sorts the query results according to the specified column. The syntax is: SELECT ...FROM ...ORDER BY column1 [ASC | DESC], column2 [ASC | DESC], ..., You can sort multiple columns, with NULL values ​​appearing first by default, their position can be specified using the NULLS FIRST or NULLS LAST option, and you can use expressions to sort the results.

The meaning and usage of ORDER BY in MySQL

What is ORDER BY?

The ORDER BY clause is used to sort query results by specified columns.

Grammar:

<code>SELECT ...
FROM ...
ORDER BY column1 [ASC | DESC], column2 [ASC | DESC], ...</code>

Among them:

• column1, column2 ... : Column name to be sorted
• ASC: Sort in ascending order (from small to large)
• DESC: Sort in descending order (from large to small)

Usage:

1. Single column sort:

Use a single column name to sort the results Sort:

<code>SELECT * FROM table ORDER BY column1 ASC;</code>

2. Multiple column sorting:

Use multiple column names to sort the results in the specified order:

<code>SELECT * FROM table ORDER BY column1 ASC, column2 DESC;</code>

3. NULL value handling:

By default, NULL values ​​appear first in the sort. Use the NULLS FIRST or NULLS LAST option to specify where NULL values ​​appear:

<code>SELECT * FROM table ORDER BY column1 ASC NULLS FIRST;</code>

4. Expression sorting:

You can use expressions to sort the results:

<code>SELECT * FROM table ORDER BY column1 * 2 DESC;</code>

Example:

The following example sorts by city name in ascending order:

<code>SELECT * FROM cities ORDER BY city_name ASC;</code>

The following example sorts by population in descending order and by city name in ascending order:

<code>SELECT * FROM cities ORDER BY population DESC, city_name ASC;</code>

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