Crate sibyl

Sibyl is an OCI-based driver for Rust applications to interface with Oracle databases.

Example

use sibyl as oracle; // pun intended :)

fn main() -> Result<(),Box<dyn std::error::Error>> {
    let dbname = std::env::var("DBNAME")?;
    let dbuser = std::env::var("DBUSER")?;
    let dbpass = std::env::var("DBPASS")?;

    let oracle = oracle::env()?;
    let conn = oracle.connect(&dbname, &dbuser, &dbpass)?;
    let stmt = conn.prepare("
        SELECT first_name, last_name, hire_date
          FROM (
                SELECT first_name, last_name, hire_date
                     , row_number() OVER (ORDER BY hire_date) ord
                  FROM hr.employees
                 WHERE hire_date >= :hire_date
               )
         WHERE ord = 1
    ")?;
    let date = oracle::Date::from_string("January 1, 2005", "MONTH DD, YYYY", &oracle)?;
    let mut rows = stmt.query(&[ &date ])?;
    if let Some( row ) = rows.next()? {
        let first_name : Option<&str> = row.get(0)?;
        let last_name : &str = row.get(1)?.unwrap();
        let name = first_name.map_or(last_name.to_string(),
            |first_name| format!("{}, {}", last_name, first_name)
        );
        let hire_date : oracle::Date = row.get(2)?.unwrap();
        let hire_date = hire_date.to_string("fmMonth DD, YYYY")?;

        println!("{} was hired on {}", name, hire_date);
    } else {
        println!("No one was hired after {}", date.to_string("fmMonth DD, YYYY")?);
    }
    Ok(())
}

Notes on Building

Sibyl needs an installed Oracle client in order to link either to OCI.DLL on Windows or to libclntsh.so on Linux. The cargo build needs to know where that library is. You can provide that information via environment variable OCI_LIB_DIR. On Linux it would be the path to the lib directory with libclntsh.so. For example, you might build sibyl’s example as:

OCI_LIB_DIR=/usr/lib/oracle/19.12/client64/lib cargo build --examples

On Windows the process is similar if the target environment is gnu. There the OCI_LIB_DIR would point to the directory with oci.dll:

set OCI_LIB_DIR=%ORACLE_HOME%\bin
cargo build --examples

However, for msvc environment the OCI_LIB_DIR must point to the directory with oci.lib. For example, you might build provided example application as:

set OCI_LIB_DIR=%ORACLE_HOME%\oci\lib\msvc
cargo build --examples

Usage

Environment

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 and then passed around:

fn main() {
    let oracle = sibyl::env().expect("Oracle OCI environment");
    // ...
}

Note that some functions will need a direct reference to this handle, so instead of passing it around some applications might prefer to create it statically:

use sibyl::Environment;
use lazy_static::lazy_static;

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:

use sibyl::TimestampTZ;

let current_timestamp = TimestampTZ::from_systimestamp(&ORACLE)?;

Connections

Use Environment::connect method to connect to a database:

fn main() -> Result<(),Box<dyn std::error::Error>> {
    let dbname = std::env::var("DBNAME")?;
    let dbuser = std::env::var("DBUSER")?;
    let dbpass = std::env::var("DBPASS")?;
    let oracle = sibyl::env()?;

    let conn = oracle.connect(&dbname, &dbuser, &dbpass)?;
    // ...
    Ok(())
}

Where dbname can be any database reference/address that is acceptable to Oracle clients - from local TNS name to Eazy Connect identifier to a connect descriptor.

SQL Statement Execution

All SQL or PL/SQL statements must be prepared before they can be executed:

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:

let rows = stmt.query(&[ &103 ])?;

or binding :id by name as:

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:

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_rows = stmt.execute_into(&[
    &( ":DEPARTMENT_NAME", "Security" ),
    &( ":MANAGER_ID",      ""         ),
    &( ":LOCATION_ID",     1700      ),
], &mut [
    &mut ( ":DEPARTMENT_ID", &mut department_id )
])?;
assert_eq!(num_rows, 1);
assert!(!stmt.is_null(":DEPARTMENT_ID")?);
assert!(department_id > 0);

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 previous SELECT example):

let mut employees = HashMap::new();

let mut rows = stmt.query(&[ &103 ])?;
while let Some( row ) = rows.next()? {
    let employee_id : u32 = row.get(0)?.unwrap();
    let last_name : &str = row.get(1)?.unwrap();
    let first_name : Option<&str> = row.get(2)?;
    let name = first_name.map_or(last_name.to_string(),
        |first_name| format!("{}, {}", last_name, first_name)
    );
    employees.insert(employee_id, name);
}

There are a few notable points of interest in the last example:

• Sibyl uses 0-based column indexing in a projection.
• Column values are returned as an Option. However, if a column is declared as NOT NULL, like EMPLOYEE_ID and LAST_NAME, the result will always be Some and 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 a String.

Note that sibyl can also identify columns by their names. The row processing loop of the previous example can be written as:

while let Some( row ) = rows.next()? {
    let employee_id : u32 = row.get("EMPLOYEE_ID")?.unwrap();
    let last_name : &str  = row.get("LAST_NAME")?.unwrap();
    let first_name : Option<&str> = row.get("FIRST_NAME")?;
    let name = first_name.map_or(last_name.to_string(), |first_name| format!("{}, {}", last_name, first_name));
    employees.insert(employee_id, name);
}

Oracle Data Types

Sibyl provides API to access several Oracle native data types.

Number

use sibyl::Number;
let oracle = sibyl::env()?;

let pi = Number::pi(&oracle);
let two = Number::from_int(2, &oracle)?;
let two_pi = pi.mul(&two)?;
let h = Number::from_string("6.62607004E-34", "9D999999999EEEE", &oracle)?;
let hbar = h.div(&two_pi)?;

assert_eq!(hbar.to_string("TME")?, "1.05457180013911265115394106872506677375E-34");

Date

use sibyl::Date;
let oracle = sibyl::env()?;

let mar28_1996 = Date::from_string("28-MAR-1996", "DD-MON-YYYY", &oracle)?;
let next_monday = mar28_1996.next_week_day("MONDAY")?;

assert_eq!(next_monday.to_string("DL")?, "Monday, April 01, 1996");

Timestamp

There are 3 types of timestamps:

• Timestamp which is equivalent to Oracle’s TIMESTAMP,
• TimestampTZ - TIMESTAMP WITH TIME ZONE,
• TimestampLTZ - TIMESTAMP WITH LOCAL TIME ZONE

use sibyl::TimestampTZ;
let oracle = sibyl::env()?;

let ts = TimestampTZ::from_string(
    "July 20, 1969 8:18:04.16 pm UTC",
    "MONTH DD, YYYY HH:MI:SS.FF PM TZR",
    &oracle
)?;
assert_eq!(
    ts.to_string("YYYY-MM-DD HH24:MI:SS.FF TZR", 3)?,
    "1969-07-20 20:18:04.160 UTC"
);

Interval

There are 2 types of intervals:

• IntervalYM which is eqivalent to Oracle’s INTERVAL YEAR TO MONTH,
• IntervalDS - INTERVAL DAY TO SECOND

use sibyl::{ TimestampTZ, IntervalDS };
let oracle = sibyl::env()?;

let launch  = TimestampTZ::with_datetime(1969, 7, 16, 13, 32,  0, 0, "UTC", &oracle)?;
let landing = TimestampTZ::with_datetime(1969, 7, 24, 16, 50, 35, 0, "UTC", &oracle)?;
let duration : IntervalDS = landing.subtract(&launch)?;

assert_eq!(duration.to_string(1,3)?, "+8 03:18:35.000");

RowID

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.

let stmt = conn.prepare("
    SELECT manager_id
      FROM hr.employees
     WHERE employee_id = :id
       FOR UPDATE
")?;
let mut rows = stmt.query(&[ &107 ])?;
if let Some( row ) = rows.next()? {
    let rowid = row.get_rowid()?;

    let manager_id: u32 = row.get(0)?.unwrap();
    assert_eq!(manager_id, 102);

    let stmt = conn.prepare("
        UPDATE hr.employees
           SET manager_id = :manager_id
         WHERE rowid = :row_id
    ")?;
    let num_updated = stmt.execute(&[
        &( ":MANAGER_ID", 102 ),
        &( ":ROW_ID",  &rowid )
    ])?;
    assert_eq!(num_updated, 1);
}

Cursors

Cursors can be returned explicitly:

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:

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()?;
    // ...
}

Structs

Connection

Represents a user session

Cursor

Cursors - implicit results and REF CURSOR - from an executed PL/SQL statement

Date

Represents Oracle DATE

Environment

Represents an OCI environment.

Number

Represents OTS types NUMBER, NUMERIC, INT, SHORTINT, REAL, DOUBLE PRECISION, FLOAT and DECIMAL.

Raw

Represents RAW and LONG RAW data types.

Row

A row in the returned result set

Rows

Result set of a query

Statement

Represents a prepared for execution SQL or PL/SQL statement

Varchar

Represents Oracle character types - VARCHAR, LONG, etc.

Enums

Cache

LOB cache control flags

CharSetForm

Character set form

ColumnType

Column data type.

Error

Represents possible errors returned from Sibyl

Traits

Ctx

Both OCIDateTime and OCIInterval can be invoked in an OCI environment or a user session context. This trait specifies protocol that Timestamp and Interval use to function in either context.

Env

FromSql

A trait for types which instances can be created from the returned Oracle values.

Position

Allows parameter or column identification by either its numeric position or its name

SqlInArg

A trait for types that can be used as SQL statement IN arguments

SqlOutArg

A trait for types that can be used as SQL statement OUT arguments

ToSql

A trait for types that can be used as SQL IN arguments

ToSqlOut

A trait for types that can be used as SQL OUT arguments

Functions

env

Returns a new environment handle, which is then used by the OCI functions.

Type Definitions

BFile

BLOB

CLOB

IntervalDS

IntervalYM

Result

RowID

Timestamp

TimestampLTZ

TimestampTZ