ORDER BY clause

Capella Operational

reference

The ORDER BY clause sorts the result-set by one or more columns, in ascending or descending order.

Purpose

In a SELECT statement, the ORDER BY clause sorts the result-set in ascending or descending order, based on one or more fields or expressions of those fields in the projection.

Prerequisites

For you to select data from a document or keyspace, you must have the query_select privilege on the document or keyspace. For more details about user roles, see Authorization.

Syntax

order-by-clause ::= 'ORDER' 'BY' ordering-term ( ',' ordering-term )*

Ordering Term

ordering-term ::= expr ( 'ASC' | 'DESC' )? ( 'NULLS' ( 'FIRST' | 'LAST' ) )?

Collation

The collation clause determines the order of the search.

ASC: The results are ordered in ascending order.
DESC: The results are ordered in descending order.

If the collation clause is missing, the default is ASC.

Nulls Ordering

The nulls ordering clause determines how NULL or MISSING values are treated when ordering the results:

NULLS FIRST: If any results evaluate to NULL or MISSING, those results ordered first.
NULLS LAST: If any results evaluate to NULL or MISSING, those results are ordered last.

If the nulls ordering clause is omitted, the default is NULLS FIRST for an ascending search with ASC, or NULLS LAST for a descending search with DESC.

Arguments

expr: [Required] The identifier or expression by which to order the query results. This may be a document field, a new expression, or an alias in the SELECT clause.

Return Values

If no ORDER BY clause is specified, the order in which the result objects are returned is undefined.

Objects are sorted first by the left-most expression in the list of expressions. Any items with the same sort value will be sorted with the next expression in the list. This process repeats until all items are sorted and all expressions in the list are evaluated.

When a field has a mix of data types, the different JSON types are sorted in the following order, from first to last:

ASC NULLS FIRST	ASC NULLS LAST	DESC NULLS FIRST	DESC NULLS LAST
MISSING	FALSE	NULL	BINARY
NULL	TRUE	MISSING	OBJECT
FALSE	NUMBER	BINARY	ARRAY
TRUE	STRING	OBJECT	STRING
NUMBER	ARRAY	ARRAY	NUMBER
STRING	OBJECT	STRING	TRUE
ARRAY	BINARY	NUMBER	FALSE
OBJECT	MISSING	TRUE	NULL
BINARY	NULL	FALSE	MISSING

ASC NULLS FIRST

ASC NULLS LAST

DESC NULLS FIRST

DESC NULLS LAST

MISSING

FALSE

NULL

BINARY

NULL

TRUE

MISSING

OBJECT

FALSE

NUMBER

BINARY

ARRAY

TRUE

STRING

OBJECT

STRING

NUMBER

ARRAY

NUMBER

STRING

OBJECT

STRING

TRUE

ARRAY

BINARY

NUMBER

FALSE

OBJECT

MISSING

TRUE

NULL

BINARY

NULL

FALSE

MISSING

NULL values include JSON NULL.
String comparison is done using a raw byte collation of UTF8 encoded strings. The ascending order is lowercase, then uppercase, then accented letters.
Arrays are sorted in order of the first element in each array, then the second element in each array, and so on. In an ascending sort, longer arrays are sorted after shorter arrays, where all the elements are equal as far as the end of the shorter array.
Objects are first sorted in order of size. In an ascending sort, larger objects are sorted after shorter objects. Where objects are the same size, objects are sorted in order of the first key in each object, then the first value in each object, then the second key in each object, then the second value in each object, and so on.
SQL++ always sorts the key-value pairs within each object by key in ascending string order before comparison or ordering.

Examples

List cities in descending order and then landmarks in ascending order
List the names of hotels and landmarks resulting from a UNION query

Example 1. List cities in descending order and then landmarks in ascending order

SELECT city, name
FROM landmark
ORDER BY city DESC, name ASC
LIMIT 5;

Results:

[
  {
    "city": "Évreux",
    "name": "Cafe des Arts"
  },
  {
    "city": "Épinal",
    "name": "Marché Couvert (covered market)"
  },
  {
    "city": "Épinal",
    "name": "Musée de l'Image/Imagerie d'Épinal"
  },
  {
    "city": "Yosemite Valley",
    "name": "Lower Yosemite Fall"
  },
  {
    "city": "Yosemite Valley",
    "name": "Mirror Lake/Meadow"
  }
]

Example 2. List the names of hotels and landmarks resulting from a UNION query

SELECT name AS sort, type
  FROM landmark
UNION SELECT name AS sort, type
  FROM hotel
ORDER BY sort ASC
LIMIT 5;

Results:

[
  {
    "sort": "&quot;Hippie Temptation&quot; house",
    "type": "landmark"
  },
  {
    "sort": "'La Mirande Hotel",
    "type": "hotel"
  },
  {
    "sort": "'The Argyll Arms Hotel",
    "type": "landmark"
  },
  {
    "sort": "'Visit the Hut of the Shadows and other End of the Road sculptures",
    "type": "landmark"
  },
  {
    "sort": "02 Shepherd's Bush Empire",
    "type": "landmark"
  }
]

Note that the name field in the first SELECT statement and the name field in the second SELECT statement give two different result expressions, so you cannot use the name field to order all the results of the UNION query together. To do this, you must give the name fields in the two SELECT statements an identical alias, and order the results by that alias.