UPDATE

UPDATE replaces a document that already exists with updated values.

Prerequisites

RBAC Privileges

User executing the UPDATE statement must have the Query Update privilege on the target keyspace. If the statement has any clauses that needs data read, such as SELECT clause, or RETURNING clause, then Query Select privilege is also required on the keyspaces referred in the respective clauses. For more details about user roles, see Authorization.

For example,

To execute the following statement, user must have the Query Update privilege on `travel-sample`.
```
UPDATE `travel-sample` SET foo = 5
```
To execute the following statement, user must have the Query Update privilege on the `travel-sample` and Query Select privilege on `beer-sample`.
```
UPDATE `travel-sample`
SET foo = 9
WHERE city IN (SELECT RAW city FROM `beer-sample` WHERE type = "brewery")
```
To execute the following statement, user must have the Query Update privilege on `travel-sample` and Query Select privilege on `travel-sample`.
```
UPDATE `travel-sample`
SET city = "San Francisco"
WHERE lower(city) = "sanfrancisco"
RETURNING *
```

Couchbase Server 6.5.1

In Couchbase Server 6.5.1, a user with the Data Writer privilege may set documents to expire. When the document expires, the data service deletes the document, even though the user may not have the Query Delete privilege.

Syntax

UPDATE update-target [update-hint] [set-clause] [unset-clause] [where-clause] [limit-clause] [returning-clause]

Update Target

update-target ::= keyspace-ref [ [ AS ] alias ]

( namespace ':' )? keyspace ( 'AS'? alias )?

The update target is the keyspace which you want to update.

Keyspace Reference

keyspace-ref ::= [ namespace ':' ] keyspace

Keyspace reference for the update target. For more details, refer to Keyspace Reference.

namespace: (Optional) The name or identifier of the namespace of the update target.
keyspace: (Required) The name or identifier of the keyspace of the update target.

AS Alias

Assigns another name to the keyspace reference. For details, refer to AS Clause.

alias: String to assign an alias.

Assigning an alias to the keyspace reference is optional. If you assign an alias to the keyspace reference, the AS keyword may be omitted.

Update Hint

You can use a USE KEYS hint on the update target to specify the keys of the data items to be updated. For details, refer to USE KEYS Clause.

SET Clause

set-clause ::= SET path '=' expr [ update-for ] [ ',' path '=' expr [ update-for ] ]*

'SET' path '=' expr update-for? (',' path '=' expr update-for?)*

Specifies the value for an attribute to be changed.

path: A path specifying the attribute to be changed.
expr: The value may be a generic expression term, a subquery, or an expression that resolves to nested array elements.

Couchbase Server 6.5.1

In Couchbase Server 6.5.1, the SET clause also supports alternative arguments which enable you to set the expiration of the document.

set-clause ::= SET ( meta '=' expiration | path '=' expr [ update-for ] ) [ ',' ( meta '=' expiration | path '=' expr [ update-for ] ) ]*

'SET' ( meta '=' expiration | path '=' expr update-for? ) ( ',' ( meta '=' expiration | path '=' expr update-for? ) )*

meta: A META().expiration expression specifying the expiration property of the document being updated.
expiration: An integer, or an expression resolving to an integer, representing the document expiration in seconds.

If the document expiration is not specified, it defaults to 0, meaning the document expiration is the same as the bucket expiration.

UNSET Clause

unset-clause ::= UNSET path [ update-for ] [ ',' path [ update-for ] ]*

'UNSET' path update-for? (',' path update-for?)*

Removes the specified attribute from the document.

path: A path specifying the attribute to be removed.

Couchbase Server 6.5.1

In Couchbase Server 6.5.1, you cannot use the UNSET clause to unset the document expiration. To unset the document expiration, you can either set the document expiration to 0, or simply update the document without specifying the document expiration.

FOR Clause

update-for ::= ( FOR [ name-var ':' ] var ( IN | WITHIN ) path [ ',' [ name-var ':' ] var ( IN | WITHIN ) path ]* )+ [ WHEN cond ] END

('FOR' (name-var ':')? var ('IN' | 'WITHIN') path (',' (name-var ':')? var ('IN' | 'WITHIN') path)*)+ ('WHEN' cond)? 'END'

path ::= identifier [ '[' expr ']' ]* [ '.' path ]

'identifier ('[' expr ']')* ( '.' path )?

Uses the FOR statement to iterate over a nested array to SET or UNSET the given attribute for every matching element in the array. The FOR clause can evaluate functions and expressions, and the UPDATE statement supports multiple nested FOR expressions to access and update fields in nested arrays. Additional array levels are supported by chaining the FOR clauses.

WHERE Clause

where-clause ::= WHERE cond

Specifies the condition that needs to be met for data to be updated. Optional.

LIMIT Clause

limit-clause ::= LIMIT expr

Specifies the greatest number of objects that can be updated. This clause must have a non-negative integer as its upper bound. Optional.

RETURNING Clause

returning-clause ::= RETURNING ( result-expr [ ',' result-expr ]* | ( RAW | ELEMENT | VALUE ) expr )

'RETURNING' (result-expr (',' result-expr)* | ('RAW' | 'ELEMENT' | 'VALUE') expr)

Specifies the information to be returned by the operation as a query result. For more details, refer to RETURNING Clause.

Examples

For some of these examples, the Query Workbench may warn you that the query has no WHERE clause and will update all documents. In this case, you can ignore the warning: the USE KEYS hint in these examples ensures that the query updates only one document.

Example 1. Set an attribute

The following statement sets the nickname of the landmark "Tradeston Pedestrian Bridge" to "Squiggly Bridge".

UPDATE `travel-sample` USE KEYS "landmark_10090" SET nickname = "Squiggly Bridge" RETURNING `travel-sample`.nickname;

[
  {
    "nickname": "Squiggly Bridge"
  }
]

Example 2. Unset an attribute

This statement removes the nickname attribute from the travel-sample keyspace for the document with the key landmark_10090.

UPDATE `travel-sample` USE KEYS "landmark_10090" UNSET nickname RETURNING `travel-sample`.name;

[
  {
    "name": "Tradeston Pedestrian Bridge"
  }
]

Example 3. Set attributes in an array

This statement sets the codeshare attribute for each element in the schedule array for document route_10003 in the travel-sample keyspace.

UPDATE `travel-sample` t USE KEYS "route_10003" SET s.codeshare = NULL FOR s IN schedule END RETURNING t;

[
    {
        "t": {
            "airline": "AF",
            "airlineid": "airline_137",
            "destinationairport": "ATL",
            "distance": 654.9546621929924,
            "equipment": "757 739",
            "id": 10003,
            "schedule": [
                {
                    "codeshare": null,
                    "day": 0,
                    "flight": "AF986",
                    "utc": "22:26:00"
                },
                ...
                {
                    "codeshare": null,
                    "day": 6,
                    "flight": "AF540",
                    "utc": "11:07:00"
                }
            ],
            "sourceairport": "TPA",
            "stops": 0,
            "type": "route"
        }
    }
]

Example 4. Set nested array elements

UPDATE `travel-sample` AS h USE KEYS "hotel_10025"
SET i.ratings = OBJECT_ADD(i.ratings, "new", "new_value" ) FOR i IN reviews END
RETURNING h.reviews[*].ratings;

[
  {
    "ratings": [
      {
        "Cleanliness": 5,
        "Location": 4,
        "Overall": 4,
        "Rooms": 3,
        "Service": 5,
        "Value": 4,
        "new": "new_value"
      },
      {
        "Business service (e.g., internet access)": 4,
        "Check in / front desk": 4,
        "Cleanliness": 4,
        "Location": 4,
        "Overall": 4,
        "Rooms": 3,
        "Service": 3,
        "Value": 5,
        "new": "new_value"
      }
    ]
  }
]

Example 5. Access nested arrays

Query

UPDATE `travel-sample` AS h USE KEYS "hotel_10025"
UNSET i.new FOR i IN
  (ARRAY j.ratings FOR j IN reviews END)
END
RETURNING h.reviews[*].ratings;

Result

[
  {
    "ratings": [
      {
        "Cleanliness": 5,
        "Location": 4,
        "Overall": 4,
        "Rooms": 3,
        "Service": 5,
        "Value": 4
      },
      {
        "Business service (e.g., internet access)": 4,
        "Check in / front desk": 4,
        "Cleanliness": 4,
        "Location": 4,
        "Overall": 4,
        "Rooms": 3,
        "Service": 3,
        "Value": 5
      }
    ]
  }
]

Example 6. Update a document with the results of a subquery

Query

UPDATE `travel-sample` AS a
SET hotels =
  (SELECT  h.name, h.id
  FROM  `travel-sample` AS h
  WHERE h.type = "hotel" AND h.city = "Nice")
WHERE a.faa ="NCE"
RETURNING a;

Result

[
  {
    "a": {
      "airportname": "Cote D\\'Azur",
      "city": "Nice",
      "country": "France",
      "faa": "NCE",
      "geo": {
        "alt": 12,
        "lat": 43.658411,
        "lon": 7.215872
      },
      "hotels": [
        {
          "id": 20419,
          "name": "Best Western Hotel Riviera Nice"
        },
        ...
        {
          "id": 20421,
          "name": "NH Nice"
        }
      ],
      "icao": "LFMN",
      "id": 1354,
      "type": "airport",
      "tz": "Europe/Paris"
    }
  }
]

Example 7. Update a document and set expiration

Couchbase Server 6.5.1

Update a document and set the expiration to 1 week.

Query

UPDATE `travel-sample` t USE KEYS "route_10003"
SET meta(t).expiration = 7*24*60*60,
s.codeshare = NULL FOR s IN schedule END;

Example 8. Update a document and preserve expiration

Couchbase Server 6.5.1

Query

UPDATE `travel-sample` t USE KEYS "route_10003"
SET meta(t).expiration = meta(t).expiration,
s.codeshare = NULL FOR s IN schedule END;

Example 9. Update a document and unset expiration

Couchbase Server 6.5.1

Set the document expiration to 0 to unset the document expiration. (In this case, the document expiration defaults to be the same as the bucket expiration.)

Query

UPDATE `travel-sample` t USE KEYS "route_10003"
SET meta(t).expiration = 0,
s.codeshare = NULL FOR s IN schedule END;

Alternatively, if you update the document without specifying the document expiration, the document expiration defaults to 0.

Query

UPDATE `travel-sample` t USE KEYS "route_10003"
SET s.codeshare = NULL FOR s IN schedule END;