Sibyl is an OCI-based driver for Rust applications to interface with Oracle databases.
```rust use sibyl as oracle; // pun intended :)
fn main() -> Result<(), Boxif let to retrieve it
if let Some( row ) = rows.next()? {
// Note that sibyl uses 0-based column indexes.
// LASTNAME is retrieved as a &str. This is fast as it borrows directly from
// the column buffer. However, it will be accessible only within the current
// scope, i.e. only during the lifetime of the current row.
// LASTNAME is NOT NULL, therefore it is safe to simply unwrap it.
let lastname = row.get::<&str>(0)?.unwrap();
let name =
// FIRSTNAME is NULL-able
if let Some( firstname ) = row.get::<&str>(1)? {
format!("{}, {}", lastname, firstname)
} else {
lastname.tostring()
}
;
let hiredate = row.get::
println!("{} was hired {}", name, hire_date);
} else {
println!("No one was hired after {}", date.to_string("YYYY-MM-DD")?);
}
Ok(())
} ```
Sibyl needs an installed Oracle client in order to link either to OCI.DLL on Windows or to libclntsh.so on Linux. It is expected that on Windows the directory with OCI.DLL is listed in the PATH. On Linux, depending on the kind of Oracle client, an additional manual configuration might be needed. Oracle client's lib directory needs to be present in ld.so.conf and a link to libclntsh.so should exist in a directory searched by linkers - /lib64 for example.
The OCI environment handle must be created before any other OCI function can be called. While there can be many environments - for example, one can create an environment per connection - usually one is enought. Sibyl initializes it to be the most compatible with Rust requirements - thread-safe using UTF8 character encoding. That single environment handle can be created in main:
rust
fn main() {
let oracle = sibyl::env().expect("Oracle OCI environment");
// ...
}
Note however that some function will need a direct refrence to this handle, so instead of passing it around some applications might create it statically:
```rust
use sibyl::Environment;
use lazystatic::lazystatic;
lazy_static!{
pub static ref ORACLE : Environment = sibyl::env().expect("Oracle OCI environment");
}
Then later one would be able to create, for example, a current timestamp as:
rust
use sibyl::TimestampTZ;
let currenttimestamp = TimestampTZ::fromsystimestamp(&ORACLE)?; ```
Use Environment::connect method to connect to a database:
rust
fn main() {
let oracle = sibyl::env().expect("Oracle OCI environment");
let conn = oracle.connect("dbname", "username", "password").expect("New database connection");
// ...
}
Where dbname can be any name that is acceptable by Oracle clients - from local TNS name to Eazy Connect identifier to a connect descriptor.
All SQL or PL/SQL statements must be prepared before they can be executed:
rust
let stmt = conn.prepare("
SELECT employee_id, last_name, first_name
FROM hr.employees
WHERE manager_id = :id
ORDER BY employee_id
")?;
A prepared statement can be executed either with the query or execute or execute_into methods:
- query is used for SELECT statements. In fact, it will complain if you try to query any other statement.
- execute is used for all other, non-SELECT, DML and DDL that do not have OUT parameters.
- execute_into is used with DML and DDL that have OUT parameters.
query and execute take a slice of IN arguments, which can be specified as positional arguments or as name-value tuples. For example, to execute the above SELECT we can call query using a positional argument as:
rust
let rows = stmt.query(&[ &103 ])?;
or binding :id by name as:
rust
let rows = stmt.query(&[
&( ":id", 103 )
])?;
In most cases which binding style to use is a matter of convenience and/or personal preferences. However, in some cases named arguments would be preferable and less ambiguous. For example, statement changes during development might force the change in argument positions. Also SQL and PL/SQL statements have different interpretation of a parameter position. SQL statements create positions for every parameter but allow a single argument to be used for the primary parameter and all its duplicares. PL/SQL on the other hand creates positions for unique parameter names and this might make positioning arguments correctly a bit awkward when there is more than one "duplicate" name in a statement.
execute_into allows execution of statements with OUT parameters. For example:
rust
let stmt = conn.prepare("
INSERT INTO hr.departments
( department_id, department_name, manager_id, location_id )
VALUES ( hr.departments_seq.nextval, :department_name, :manager_id, :location_id )
RETURNING department_id
INTO :department_id
")?;
let mut department_id: u32 = 0;
let num_inserted = stmt.execute(&[
&( ":department_name", "Security" ),
&( ":manager_id", "" ),
&( ":location_id", 1700 ),
], &mut [
&mut ( ":department_id", &mut department_id )
])?;
execute and execute_into return the number of rows affected by the statement. query returns what is colloquially called a "streaming iterator" which is typically iterated using while. For example (continuing the SELECT example from above):
```rust
let employees = HashMap::new();
let rows = stmt.query(&[ &103 ])?;
while let Some( row ) = rows.next()? {
let employeeid = row.get::
There are a few notable elements in the last example:
- Sibyl uses 0-based indexing of columns in a projection.
- Column values are returned as anOption. However if a column declared as NOT NULL, like EMPLOYEE_ID and LAST_NAME, the result will always beSomeand therefore can be safely unwrapped.
- LAST_NAME and FIRST_NAME are retrieved as&str. This is fast as they are borrowed directly from the respective column buffers. However those values will only be valid during the lifetime of the row. If the value needs to continue to exist beyond the lifetime of a row, it should be retrieved as aString`.
Sibyl provides API to access several Oracle native data types.
```rust use sibyl::Number;
let pi = Number::pi(&oracle); let two = Number::fromint(2, &oracle); let twopi = pi.mul(two)?; let h = Number::fromstring("6.62607004E-34", "9D999999999EEEE", &oracle)?; let hbar = h.div(twopi)?; println!("{}", hbar.to_string("TME")?); ```
```rust use sibyl::Date;
let apr181996 = Date::fromstring("18-APR-1996", "DD-MON-YYYY", &oracle)?; let nextmonday = apr181996.nextweekday("MONDAY")?; println!("{}", nextmonday.tostring("MM/DD/YYYY")?); ```
There are 3 types of timestamps:
- Timestamp which is equivalent to Oracle TIMESTAMP,
- TimestampTZ - TIMESTAMP WITH TIME ZONE,
- TimestampLTZ - TIMESTAMP WITH LOCAL TIME ZONE
```rust use sibyl::TimestampTZ;
let ts = oracle::TimestampTZ::fromstring( "July 20, 1969 8:18:04.16 pm UTC", "MONTH DD, YYYY HH:MI:SS.FF PM TZR", &oracle )?; let txt = ts.tostring("Dy, Mon DD, YYYY HH:MI:SS.FF PM TZR", 3)?;
```
There are 2 types of intervals:
- IntervalYM which is eqivalent to Oracle INTERVAL YEAR TO MONTH,
- IntervalDS - INTERVAL DAY TO SECOND
```rust use sibyl::{ TimestampTZ, IntervalDS };
let launch = TimestampTZ::fromdatetime(1969,7,16,13,32,0,0,"UTC", &oracle)?; let landing = TimestampTZ::fromdatetime(1969,7,24,16,50,35,0,"UTC", &oracle)?; let duration : IntervalDS = landing.subtract(&launch)?;
asserteq!("+8 03:18:35.000", duration.tostring(1,3)?); ```
Oracle ROWID can be selected and retrieved explicitly into an instance of the RowID. However, one interesting case is SELECT FOR UPDATE queries where Oracle returns ROWIDs implicitly. Those can be retrieved using Row::get_rowid method.
```rust let stmt = conn.prepare(" SELECT managerid FROM hr.employees WHERE employeeid = :id FOR UPDATE ")?; let rows = stmt.query(&[ &107 ])?; let currow = rows.next()?; assert!(currow.issome()); let row = currow.unwrap();
let managerid: u32 = row.get(0)?.unwrapordefault(); asserteq!(103, manager_id);
let rowid = row.get_rowid()?;
let stmt = conn.prepare(" UPDATE hr.employees SET managerid = :managerid WHERE rowid = :rowid ")?; let numupdated = stmt.execute(&[ &( ":managerid", 102 ), &( ":rowid", &rowid ) ])?; asserteq!(1, numupdated); ```
Cursors can be returned explicitly:
rust
let stmt = conn.prepare("
BEGIN
OPEN :emp FOR
SELECT department_name, first_name, last_name, salary
FROM hr.employees e
JOIN hr.departments d
ON d.department_id = e.department_id;
END;
")?;
let mut cursor = Cursor::new(&stmt)?;
stmt.execute_into(&[], &mut [ &mut cursor ])?;
let rows = cursor.rows()?;
// ...
Or, beginning with Oracle 12.1, implicitly:
rust
let stmt = conn.prepare("
DECLARE
emp SYS_REFCURSOR;
BEGIN
OPEN emp FOR
SELECT department_name, first_name, last_name, salary
FROM hr.employees e
JOIN hr.departments d
ON d.department_id = e.department_id;
;
DBMS_SQL.RETURN_RESULT(emp);
END;
")?;
stmt.execute(&[])?;
if let Some( cursor ) = stmt.next_result()? {
let rows = cursor.rows()?;
// ...
}
Some of sibyl's tests connect to the database and expect certain objects to exist in it and certain privileges granted:
- At least the HR demo schema should be installed. If you are using Express Edition, it is already pre-installed.
- While there is no need to install other demo schemas at least MEDIA_DIR should be created (see $ORACLE_HOME/demo/schema/mk_dir.sql) and point to the directory with (a few of) the files that are provided in the demo/schema/product_media.
- Some of the LOB tests need text files that have to be created manually. Those should be UTF-16 BE encoded without BOM. The hexadecimal dump of the expected content is provided in the respective doc tests.
- A test user should be created. The user needs acccess to the HR schema and to the MEDIA_DIR directory. See etc/create_sandbox.sql for an example of how it can be accomplished.
At this time sibyl provides only the most commonly needed means to interface with the Oracle database. Some of the missing features are: - Non-blocking execution - Array interface for multi-row operations - User defined data types - PL/SQL collections and tables - Objects - JSON data - LDAP and proxy authentications - Global transactions - Session and connection pooling - High Availability - Continuous query and publish-subscribe notifications - Advanced queuing - Shards - Direct path load
Some of these features will be added in the upcoming releases. Some will be likely kept on a backburner until the need arises or they are explicitly requested. And some might never be implemented.