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Order By
========
The ORDER BY keyword is used to sort the result-set by column; by default, it sorts the records in ascending order.
SQL ORDER BY Syntax:
.. code-block:: mysql
SELECT column_name(s)
FROM table_name
ORDER BY column_name(s) ASC|DESC;
**ORDER BY Example**
The "Persons" table:
+---------+------------+----------+----------+--------+
|Id |LastName |FirstName |Address | City |
+=========+============+==========+==========+========+
| 1 | Larson | Sue |3 Cherry | Chicago|
+---------+------------+----------+----------+--------+
| 2 | Roberts | Teri |21 Brown | Chicago|
+---------+------------+----------+----------+--------+
| 3 | Peterson | Kari |30 Mell | Reno |
+---------+------------+----------+----------+--------+
To select all the persons from the table above, and also sort them by their last name, use the following SELECT statement:
.. code-block:: mysql
SELECT * FROM Persons
ORDER BY LastName;
The result-set will look like this:
+---------+------------+----------+----------+--------+
|Id |LastName |FirstName |Address | City |
+=========+============+==========+==========+========+
| 1 | Larson | Sue |3 Cherry | Chicago|
+---------+------------+----------+----------+--------+
| 3 | Peterson | Kari |30 Mell | Reno |
+---------+------------+----------+----------+--------+
| 2 | Roberts | Teri |21 Brown | Chicago|
+---------+------------+----------+----------+--------+
Without using "ORDERBY" in the following query, the result-set will be non-deterministic, and could returned matching rows in a different order for each query.
ORDER BY DESC can be used to reverse the order of the result set.
.. code-block:: mysql
SELECT * FROM Persons
ORDER BY LastName DESC;
.. todo::
add something about how ORDER BY is executed. index scan vs filesort
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