.. -*- coding: utf-8 -*-
.. _RQL:
RQL syntax
----------
Reserved keywords
~~~~~~~~~~~~~~~~~
The keywords are not case sensitive.
::
DISTINCT, INSERT, SET, DELETE,
WHERE, AND, OR, NOT, EXISTS,
IN, LIKE, UNION, WITH, BEING,
TRUE, FALSE, NULL, TODAY, NOW,
LIMIT, OFFSET,
HAVING, GROUPBY, ORDERBY, ASC, DESC
Variables and Typing
~~~~~~~~~~~~~~~~~~~~
With RQL, we do not distinguish between entities and attributes. The
value of an attribute is considered an entity of a particular type (see
below), linked to one (real) entity by a relation called the name of
the attribute.
Entities and values to browse and/or select are represented in
the query by *variables* that must be written in capital letters.
There is a special type **Any**, referring to a non specific type.
We can restrict the possible types for a variable using the
special relation **is**.
The possible type(s) for each variable is derived from the schema
according to the constraints expressed above and thanks to the relations between
each variable.
Built-in types
``````````````
The base types supported are string (between double or single quotes),
integers or floats (the separator is '.'), dates and
boolean. We expect to receive a schema in which types String,
Int, Float, Date and Boolean are defined.
* `String` (literal: between double or single quotes).
* `Int`, `Float` (separator being'.').
* `Date`, `Datetime`, `Time` (literal: string YYYY/MM/DD [hh:mm] or keywords
`TODAY` and `NOW`).
* `Boolean` (keywords `TRUE` and `FALSE`).
* `Keyword` NULL.
Operators
~~~~~~~~~
Logical Operators
`````````````````
::
AND, OR, NOT, ','
',' is equivalent to 'AND' but with the smallest among the priority
of logical operators (see :ref:`PriorityOperators`).
Mathematical Operators
````````````````````
::
+, -, *, /
Comparison operators
````````````````````
::
=, <, <=, >=, >, ~=, IN, LIKE
* The operator `=` is the default operator.
* The operator `LIKE` equivalent to `~=` can be used with the
special character `%` in a string to indicate that the chain
must start or finish by a prefix/suffix:
::
Any X WHERE X name ~= 'Th%'
Any X WHERE X name LIKE '%lt'
* The operator `IN` provides a list of possible values:
::
Any X WHERE X name IN ( 'chauvat', 'fayolle', 'di mascio', 'thenault')
XXX nico: "A trick <> 'bar'" wouldn't it be more convenient than
"NOT A trick 'bar'" ?
.. _PriorityOperators:
Operators priority
``````````````````
1. '*', '/'
2. '+', '-'
3. 'not'
4 'and'
5 'or'
6 ','
Search Query
~~~~~~~~~~~~
[ `DISTINCT`] <entity type> V1 (, V2) \ *
[ `GROUPBY` V1 (V2) \*] [ `ORDERBY` <orderterms>]
[ `LIMIT` <value>] [ `OFFSET` <value>]
[ `WHERE` <restriction>]
[ `WITH` V1 (, V2) \ * BEING (<query>)]
[ `HAVING` <restriction>]
[ `UNION` <query>]
:entity type:
Type of selected variables.
The special type `Any` is equivalent to not specify a type.
:restriction:
list of conditions to test successively
`V1 relation V2 | <static value>`
:orderterms:
Definition of the selection order: variable or column number followed by
sorting method ( `ASC`, `DESC`), ASC is the default.
:note for grouped queries:
For grouped queries (e.g., a clause `GROUPBY`), all
selected variables must be aggregated or grouped.
Sorting and groups
``````````````````
- For grouped queries (e.g. with a GROUPBY clause), all
selected variables should be grouped.
- To group and/or sort by attributes, we can do: "X,L user U, U
login L GROUPBY L, X ORDERBY L"
- If the sorting method (SORT_METHOD) is not specified, then the sorting is
ascendant.
- Aggregate Functions: COUNT, MIN, MAX, AVG, SUM
Negation
````````
* A query such as `Document X WHERE NOT X owned_by U` means "the
documents have no relation `owned_by`".
* But the query `Document X WHERE NOT X owned_by U, U login "syt"`
means "the documents have no relation `owned_by` with the user
syt". They may have a relation "owned_by" with another user.
Identity
````````
You can use the special relation `identity` in a query to
add an identity constraint between two variables. This is equivalent
to ``is`` in python::
Any A WHERE A comments B, A identity B
return all objects that comment themselves. The relation
`identity` is especially useful when defining the rules for securities
with `RQLExpressions`.
Limit / offset
``````````````
::
Any P ORDERBY N LIMIT 5 OFFSET 10 WHERE P is Person, P firstname N
Function calls
``````````````
::
Any UPPER(N) WHERE P firstname N
Functions on string: UPPER, LOWER
Exists
``````
::
Any X ORDERBY PN,N
WHERE X num N, X version_of P, P name PN,
EXISTS(X in_state S, S name IN ("dev", "ready"))
OR EXISTS(T tags X, T name "priority")
Optional relations (Left outer join)
````````````````````````````````````
* They allow you to select entities related or not to another.
* You must use the `?` behind the variable to specify that the relation
toward it is optional:
- Anomalies of a project attached or not to a version ::
Any X, V WHERE X concerns P, P eid 42, X corrected_in V?
- All cards and the project they document if necessary ::
Any C, P WHERE C is Card, P? documented_by C
Any T,P,V WHERE T is Ticket, T concerns P, T done_in V?
Having
``````
::
Any X GROUPBY X WHERE X knows Y HAVING COUNT(Y) > 10
Subqueries
``````````
::
(Any X WHERE X is Person) UNION (Any X WHERE X is Company)
DISTINCT Any W, REF
WITH W, REF BEING
(
(Any W, REF WHERE W is Workcase, W ref REF,
W concerned_by D, D name "Logilab")
UNION
(Any W, REF WHERE W is Workcase, W ref REF, '
W split_into WP, WP name "WP1")
)
Examples
````````
- *Search for the object of identifier 53*
::
Any WHERE X
X eid 53
- *Search material such as comics, owned by syt and available*
::
Any X WHERE X is Document
X occurence_of F, F class C, C name 'Comics'
X owned_by U, U login 'syt'
X available TRUE
- *Looking for people working for eurocopter interested in training*
::
Any P WHERE
P is Person, P work_for S, S name 'Eurocopter'
P interested_by T, T name 'training'
- *Search note less than 10 days old written by jphc or ocy*
::
Any N WHERE
N is Note, N written_on D, D day> (today -10),
N written_by P, P name 'jphc' or P name 'ocy'
- *Looking for people interested in training or living in Paris*
::
Any P WHERE
P is Person, (P interested_by T, T name 'training') OR
(P city 'Paris')
- *The name and surname of all people*
::
Any N, P WHERE
X is Person, X name N, X first_name P
Note that the selection of several entities generally force
the use of "Any" because the type specification applies otherwise
to all the selected variables. We could write here
::
String N, P WHERE
X is Person, X name N, X first_name P
Note: You can not specify several types with * ... where X is FirstType or X is SecondType*.
To specify several types explicitely, you have to do
::
Any X where X is in (FirstType, SecondType)
Insertion query
~~~~~~~~~~~~~~~~
`INSERT` <entity type> V1 (, <entity type> V2) \ * `:` <assignments>
[ `WHERE` <restriction>]
:assignments:
list of relations to assign in the form `V1 relationship V2 | <static value>`
The restriction can define variables used in assignments.
Caution, if a restriction is specified, the insertion is done for
*each line result returned by the restriction*.
- *Insert a new person named 'foo'*
::
INSERT Person X: X name 'foo'
- *Insert a new person named 'foo', another called 'nice' and a 'friend' relation
between them*
::
INSERT Person X, Person Y: X name 'foo', Y name 'nice', X friend Y
- *Insert a new person named 'foo' and a 'friend' relation with an existing
person called 'nice'*
::
INSERT Person X: X name 'foo', X friend Y WHERE name 'nice'
Update and relation creation queries
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
`SET` <assignements>
[ `WHERE` <restriction>]
Caution, if a restriction is specified, the update is done *for
each result line returned by the restriction*.
- *Renaming of the person named 'foo' to 'bar' with the first name changed*
::
SET X name 'bar', X first_name 'original' WHERE X is Person, X name 'foo'
- *Insert a relation of type 'know' between objects linked by
the relation of type 'friend'*
::
SET X know Y WHERE X friend Y
Deletion query
~~~~~~~~~~~~~~
`DELETE` (<entity type> V) | (V1 relation v2 ),...
[ `WHERE` <restriction>]
Caution, if a restriction is specified, the deletion is made *for
each line result returned by the restriction*.
- *Deletion of the person named 'foo'*
::
DELETE Person X WHERE X name 'foo'
- *Removal of all relations of type 'friend' from the person named 'foo'*
::
DELETE X friend Y WHERE X is Person, X name 'foo'