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Eclipse JNoSQL Aphrodite
Eclipse JNoSQL Aphrodite is the project that contains the syntax query to JNoSQL API.
The general concepts about the statements:
- All instructions end with a break like
\n - It is case sensitive
- All keywords must be in lowercase
- The goal is to look like SQL, however simpler
- The scope of this API is to key-value, column and document type, once Apache Tinkerpop already have one to Graph.
- Even with this query, a specific implementation may not support an operation, condition, so on. E.g: Column family may not support query with equals operator in a different field that is not the key field.
- The goal of the API is not about forgotten the specific behavior that there is in a particular database. These features matter, that's why there's an extensible API.
Column and Document
Select
The select statement reads one or more fields for one or more entities. It returns a result-set of the entities matching the request, where each entity contains the fields for corresponding to the query.
select_statement ::= SELECT ( select_clause | '*' )
FROM entity_name
[ WHERE where_clause ]
[ SKIP (integer) ]
[ LIMIT (integer) ]
[ ORDER BY ordering_clause ]
Sample
select * from God
select name, age ,adress.age from God order by name desc age desc
select * from God where birthday between "01-09-1988" and "01-09-1988" and salary = 12
select name, age ,adress.age from God skip 20 limit 10 order by name desc age desc
Insert
Inserting data for an entity is done using an INSERT statement:
insert_statement ::= INSERT entity_name (name = value, (`,` name = value) *) [ TTL ]
Sample:
insert God (name = "Diana", age = 10)
insert God (name = "Diana", age = 10, power = {"sun", "god"})
insert God (name = "Diana", age = 10, power = {"sun", "god"}) 1 day
Update
Updating an entity is done using an UPDATE statement:
insert_statement ::= UPDATE entity_name (name = value, (`,` name = value) *)
Sample:
update God (name = "Diana", age = 10)
update God (name = "Diana", age = 10, power = {"hunt", "moon"})
Delete
Deleting either an entity or fields uses the DELETE statement
delete_statement ::= DELETE [ simple_selection ( ',' simple_selection ) ]
FROM entity_name
WHERE where_clause
Sample:
delete from God
delete name, age ,adress.age from God
Key-value
GET
Retrieving data for an entity is done using an GET statement:
get_statement ::= GET ID (',' ID)*
Sample:
get "Diana" "Artemis"
get "Apollo"
PUT
To either insert or overrides values from a key-value database use the PUT statement.
put_statement ::= PUT {KEY, VALUE, [TTL]} (',' {KEY, VALUE [TTL]})*
Sample:
put {"Diana" , "The goddess of hunt", 10 second}
put {"Diana" , "The goddess of hunt"}
put {"Diana" , "The goddess of hunt", 10 second}, {"Aphrodite" , "The goddess of love"}
REMOVE
To delete one or more entities use the REMOVE statement
del_statement ::= GET ID (',' ID)*
Sample:
remove "Diana" "Artemis"
remove "Apollo"
WHERE
The WHERE clause specifies a filter to the result. These filters are booleans operations that are composed of one or more conditions appended with the and (AND) and or (OR) operators.
Conditions
Condition performs different computations or actions depending on whether a boolean query condition evaluates to true or false. The conditions are composed of three elements:
- Name, the data source or target, to apply the operator
- Operator, that defines comparing process between the name and the value.
- Value, that data that receives the operation.
Operators
The Operators are:
| Operator | Description |
|---|---|
| = | Equal to |
| > | Greater than |
| < | Less than |
| >= | Greater than or equal to |
| <= | Less than or equal to |
| BETWEEN | TRUE if the operand is within the range of comparisons |
| NOT | Displays a record if the condition(s) is NOT TRUE |
| AND | TRUE if all the conditions separated by AND is TRUE |
| OR | TRUE if any of the conditions separated by OR is TRUE |
| LIKE | TRUE if the operand matches a pattern |
| IN | TRUE if the operand is equal to one of a list of expressions |
The value
The value is the last element in a condition, and it defines what it 'll go to be used, with an operator, in a field target.
There are six types:
- number is a mathematical object used to count, measure and also label where if it is a decimal, will become double, otherwise, long. E.g.:
age = 20,salary = 12.12 - string one or more characters: among two double quotes
". E.g.: name = "Ada Lovelace" - Convert: convert is a function where given the first value parameter, as number or string, it will convert to the class type of the second one. E.g.:
birthday = convert("03-01-1988", java.time.LocalDate) - parameter: the parameter is a dynamic value, which means, it does not define the query, it'll replace in the execution time. The parameter is at
@followed by a name. E.g.:age = @age - array: A sequence of elements that can be either number or string that is between braces
{}. E.g.:power = {"Sun", "hunt"} - json: JavaScript Object Notation is a lightweight data-interchange format. E.g.:
siblings = {"apollo": "brother", "zeus": "father"}
SKIP
The SKIP option to a SELECT statement defines where the query should start,
LIMIT
The LIMIT option to a SELECT statement limits the number of rows returned by a query,
ORDER BY
The ORDER BY clause allows selecting the order of the returned results. It takes as argument a list of column names along with the order for the column (ASC for ascendant and DESC for the descendant, omitting the order being equivalent to ASC).
TTL
Both the INSERT and PUT commands support setting a time for data in an entity to expire. It defines the time to live of an object that is composed of the integer value and then the unit that might be day, hour, minute, second, millisecond, nanosecond. E.g.: ttl 10 second
