SQL3 / SQL:2008 - KTH · SQL3 / SQL:2008 The SQL3 standard is big and is therefore divided into parts: 1.SQL/Framework, contains information common to all parts of the standard

SQL3 / SQL:2008The SQL3 standard is big and is therefore divided into parts:

1. SQL/Framework, contains information common to all parts of the standardand describes the parts.

2. SQL/Foundation, Data definition and data maniputlation syntax andsemantics, including SQL embedded in non-object programming languages.

3. SQL/CLI (Call Level Inteface), the API for programming languages,corresponds to ODBC.

4. SQL/PSM (Persistent Stored Modules), stored routines, external routines,and procedural language extensions to SQL.

5. SQL/MED (Management of External Data) provides extensions to SQL thatdefine foreign-data wrappers and datalink types to allow SQL to manage datathat is accessible to, but not managed by, an SQL-based DBMS.

DD2471 (Lecture 08) Modern database systems & their applications Spring 2012 1 / 44

SQL3 / SQL:2008 . . .

6. SQL/OLB (Object Language Bindings), defines the syntax and symantics ofSQLJ, which is SQL embedded in Java.

7. The SQL/MM (Multimedia), which extends SQL to deal with large, complexand maybe streaming data, like video, audio and spatial data.

8. SQL/Schemata defines the Information Schema and Definition Schema,providing a common set of tools to make SQL databases and objectsself-describing.

9. SQL/JRT (Java Routines and Types), specifies the ability to invoke static Javamethods as routines from within SQL applications. It also calls for the abilityto use Java classes as SQL structured user-defined types.

10. SQL/XML, specifies SQL-based extensions for using XML in conjunction withSQL.


SQL3:2008 – row typesA row type, ”ROW TYPE”, is a sequence of pairs, name and data type, andcorresponds to either a composite attribute in EER modelling or a row in a table.E.g.:

create table person (

ssn char(11),

name row (fname varchar(25),

lname varchar(25)),

address row (streetname varchar(25),

streetno smallint,

postalcode char(6),

city varchar(25)));

insert into person values (’451112-0356’,

row(’Serafim’,’Dahl’),

row(’Blomstervagen’,12,’131 37’,’Nacka’));


SQL3:2008 – user defined types (UDT)

• DISTINCT TYPE, is the simplest form. Used to semantically distinguish datawith the same underlying structure , e.g.:

CREATE DISTINCT TYPE SocialSecurityNumber AS CHAR(11);

CREATE DISTINCT TYPE EmployeeNumber AS CHAR(11);

Note the distinction here between type and domain. A domain is a restrictionon type to clarify which values that may be stored in a table column. Thedomain is in both cases CHAR(11).

• A UDT consists, in the general case, of one or more attribute definitions, anumber (even zero) of routine declarations and a number (even zero) ofoperator declarations.

• A UDT may be specified in so many ways that an example has to be enough.Suppose that we want to represent persons:


SQL3:2008 – UDT . . .CREATE TYPE PersonType AS (

ssn SocialSecurityNumber CHECK (alive(ssn)),

firstname VARCHAR(15),

lastname VARCHAR(15))

INSTANTIABLE

NOT FINAL

REF IS SYSTEM GENERATED

INSTANCE METHOD age() RETURNS INTEGER,

INSTANCE METHOD age(ssn SocialSecurityNumber)

RETURNS PersonType;

CREATE INSTANCE METHOD age() RETURNS INTEGER;

FOR PersonType BEGIN

RETURN /* code to calculate age */

END;

CREATE INSTANCE METHOD age(ssn SocialSecurityNumber)

RETURNS PersonType

FOR PersonType BEGIN

SELF.ssn = ssn

RETURN SELF

END;


SQL3:2008 – observers and mutatorsFor each attribute in a UDT an observer function and a mutator function areautomatically created. Both may be (should be??) redefined by the user.

SQL3 uses total encapsulation (as in Smalltalk), meaning that attributes are onlyaccessible by the observer and manipulable by the mutator.

The observer for firstname in the PersonType is:

FUNCTION firstname (p PersonType) RETURNS VARCHAR(15)

RETURN p.firstname;

and the corresponding mutator:

FUNCTION firstname (p PersonType RESULT, newname VARCHAR(15))

RETURNS PersonType

BEGIN

p.firstname = newname;

RETURN p;

END;


SQL3:2008 – constructorsA constructor is created as well. The default constructor takes no arguments andsets all attributes to their defaults (which almost always is a bad idea).

The user may (must??) redefine the default constructor and a reasonableconstructor for PersonType might be:

CREATE CONSTRUCTOR METHOD PersonType (

ssn SocialSecurityNumber,

firstname VARCHAR(15),

lastname VARCHAR(15))

RETURNS PersonType

BEGIN

SET SELF.ssn = ssn;

SET SELF.firstname = firstname;

SET SELF.lastname = lastname;

RETURN SELF;

END;


SQL3:2008 – User Defined Routine (UDR)

The call for generality makes it important to be able to include functions andprocedures that are impossible to construct with the built-in facilities

E.g. if you have stored images in the database and want to present thumbnailimages for an overview it might be better to be able to generate the thumbnailimage rather than to store it in the database

A UDR can be defined as part of a UDT or as part of a schema. I may be writtenin almost any language, even directly in SQL(3)

Procedures are invoked by the command CALL and can have parameters of typeIN, OUT or INOUT as in ADA


SQL3:2008 – UDR . . .CREATE FUNCTION thumbNail (IN im ImageType)

RETURNS BOOLEAN

EXTERNAL NAME /usr/local/bin/thumbnail

LANGUAGE C

PARAMETER STYLE GENERAL

DETERMINISTIC

NO SQL;

the external executable ’thumbnail’ has to be provided by the user. TheORDBMS will link to it, store it in the database and invoke it when necessary.

’DETERMINISTIC’ means the the function always gives the same result for thesame input (= no side effects)

’NO SQL’ means the the function does not contain any SQL statements (= noembedded SQL in this case)

Other options: ’CONTAINS SQL’, ’READS SQL DATA’and ’MODIFIES SQL DATA’


SQL3:2008 – UDR, polymorphism

Polymorphism in the shape of overloading exists but with restrictions:

• methods may redefine the content of superclass methods with the samename and the same signature,

• two methods in the same schema may carry the same name as long as theydiffer in signature,

• Interesting: If no method is found that has the exact signature of the call (thatcan be inferred from the call) SQL tries to find a “closest match” and attemptsto invoke that method if one is found.


SQL3:2008 – reference types and object identity

Just as in Postgres there is an implicit ’oid’ assigned to every row in every table.

The objective is never to reuse an oid the ensure reference integrity.

They are stored in the database, may be shared among databases, and constitutea direct reference to a specific row in a specific table in a database (or, if shared, aspecific database in the actual server).


SQL3:2008 – sub- and supertypes

CREATE TYPE empType UNDER PersonType AS (

empNo employeeNumber,

position VARCHAR(10) DEFAULT ’Assistant’,

salary DECIMAL(8,2),

department VARCHAR(10),

INSTANCE METHOD isBoss () RETURNS BOOLEAN

INSTANTIABLE

NOT FINAL;

CREATE INSTANCE METHOD isBoss () RETURNS BOOLEAN

FOR empType

BEGIN

IF SELF.position=’Boss’ THEN RETURN True;

ELSE RETURN False;

ENDIF

END;

A type has the type of all its supertypes and, thus, the type system corresponds closely toclasses in OOP languages.


SQL3:2008 – sub- and supertypes . . .

A special restriction requires all types to have exactly one most specific typewhich makes it impossible to have multiple inheritance unless the types share acommon supertype

Sometimes it takes a rather strained approach to organizing types to make it work.Not so OOP

You may have to create a number of “glue” types.

You may have to create a mix of table inheritance and OO-inheritance.

The privileges to create types and subtypes are standard database privileges.


SQL3:2008 – tablesTo guarantee backwards compatibility with earlier SQL standards you must stilluse ’CREATE TABLE’ even if the table consists of just a UDT.

Tables are still the only means for persistence

Due to a complex syntax and a likewise complex semantics the variations areinfinite, e.g

CREATE TABLE employee (

info empType,

PRIMARY KEY (empNo));

or

CREATE TABLE employee OF empType (

REF IS empID SYSTEM GENERATED,

PRIMARY KEY (empNo));


SQL3:2008 – tables with references

CREATE TABLE order (

orderNo orderNumber,

item itemNo NOT NULL,

quantity INTEGER NOT NULL,

unit VARCHAR(5) NOT NULL,

client SocialSecurityNumber NOT NULL,

representative REF(empType) SCOPE employee

REFERENCES ARE CHECKED ON DELETE CASCADE,

PRIMARY KEY (orderNo));


SQL3:2008 – problems with table references

If we create a table ’client’ as

CREATE TABLE client (

info PersonType,

deductionrate SMALLINT,

latestPurchase DATE,

PRIMARY KEY (ssn));

we will spread information about persons over two tables (’empType’ is a subtypeto ’PersonType’). If we use the method regularly then we are in troubles. . .

It might be better to create the table differently:

CREATE TABLE client UNDER person(

deductionrate SMALLINT,

latestPurchase DATE);


SQL3:2008 – problems with table references . . .

Then the part of client that belongs to the person type will be stored in the persontable with the extra feature that if information about a client is deleted from theclient table then the corresponding info will automatically be erased from theperson table.

Rules are quite intuitive:• An insert is automatically distributed over tables and “supertables”.

• An update is automatically propagated to all involved rows in all involvedtables.

• A delete is also automatically proagated to all involved tables.


SQL3:2008 – collection types, ’ARRAY’So far (and it seems to stop at that), two collection types have been implemented,’ARRAY’ and ’MULTISET’.

ARRAY works approximately as in programming languages:

Suppose that we addrelative PersonType ARRAY

to the ’employee’-table. Then we can find the ssn of “closest” and “most distant”realtive by

SELECT relative[1].ssn as closestRelSsn,

relative[CARDINALITY(relative)].ssn as mostDistantRelSsn

FROM employee e

WHERE e.ssn=’451112-0356’;

All collection types have the ’CARDINALITY’ method that returns the actual numberof elements in a collection.OBS that prior to SQL3 you had to indicate the max number of elements that yourcollection could contain.


SQL3:2008 – collection types, ’MULTISET’

You may use relative MULTISET(PersonType) instead of ’ARRAY’ and ask forinformation about the relatives by

SELECT n.ssn, n.firstname

FROM employee e,

UNNEST (e.relative) AS n(ssn,firstname, lastname)

WHERE e.ssn = ’451112-0356’;


SQL3:2008 – collection types, ’MULTISET’ . . .It would be possible to represent the nested relation from lecture 1

DocumentTitle Author Date Search-words Lang code Lang

DBTheory Lindqvist 940322 database 46 swedishDahl relation

normalformODBMS Johnson 940312 persistent 0 english

Peterson transient

with (according to MS):

CREATE TABLE document (

title VARCHAR(50),

author VARCHAR(50) MULTISET,

date DATE,

search VARCHAR(50) MULTISET,

language ROW (code integer, language VARCHAR(20))

);


SQL3:2008 – Persistent Stored Modules (PSM)

PSM is an addition to SQL3 to ensure computational completeness instead of, asin SQL(1) and SQL2, merely relational completeness.

Some of these additions:• Declarations, e.g.:

DECLARE b BOOLEAN;

DECLARE a empType;

b = a.isBoss();

• IF ... THEN ... ELSE ... END IF

• CASE lowercase(x)

WHEN ’a’ THEN SET a = 1;

WHEN ’b’ THEN SET a = 2;

SET b = 1;

WHEN ’default THEN set b = 2;

END CASE;


SQL3:2008 – Persistent Stored Modules (PSM) . . .

• Repetition statements, where blocks of SQL statements can be executed and youmay loop over the result tables

• FOR x,y AS SELECT a,b FROM tab1 WHERE cond DO

...

END FOR;

• WHILE NOT b DO

...

END WHILE;

• REPEAT

...

UNTIL NOT b

END REPEAT;

• A ’CALL’ statement to execute procedures and a ’RETURN’ statement which allowsreturning the result of executing an SQL statement from a function invocation.


SQL3:2008 – exceptionsSQL3 includes exception management. It is verbose . . . .

You declare an exception and describe the action to take if an error occurs. Then you canchoose what to do after the action has been executed. You can choose to be satisfied anddo nothing more or send the signal on to enclosing environments.

DECLARE { CONTINUE | EXIT | UNDO } HANDLER

FOR SQLSTATE { sqlStatus | conditionName |

SQLEXCEPTION | SQLWARNING | NOT FOUND }

action;

DECLARE cond CONDITION

[ FOR SQLSTATE sqlStatus ]

An error (exception) signal may be explicitly sent or resent.

SIGNAL sqlStatus; RESIGNAL sqlStatus;


SQL3:2008 – triggersA trigger is a (compound) SQL statement that the DBMS execute automatically asa side effect to some event.They are set to execute prior to or after letting the event have is effect on the dataand are used to

• check input data

• enforce complex integrity requirements

• message-sending

• uphold transaction logs

• replication in distributed DBMS

CREATE TRIGGER triggername

BEFORE | AFTER event ON table

[ REFERENCING aliaslist ]

[ FOR EACH { ROW | STATEMENT } ]

[ WHEN triggercondition ]

triggercode


SQL3:2008 – triggers, example

CREATE TRIGGER setnull-trigger

BEFORE UPDATE ON employee

REFERENCING NEW ROW AS newrow

FOR EACH ROW

WHEN newrow.phone = ’’

SET newrow.phone = NULL

CREATE TRIGGER check-department

BEFORE INSERT ON employee


WHEN newrow.dept NOT IN

(SELECT name FROM department)

SIGNAL avd-not-found(newrow.dept)


SQL3:2008 – triggers, example . . .

CREATE TRIGGER update-supply

AFTER INSERT ON order


FOR EACH ROW

UPDATE supply SET volume = volume - newrow.quantity

WHERE item = newrow.item


ORDBMS – some systems

Three of the major DBMS providers – IBM, Informix and Oracle – have extendedtheir RDBMS to ORDBMS or universal servers.

They have – each with their own technique – extended their DBMS to handlepluggable modules that extends both its data storage possibilities, its type system,its optimizer and its functionality.

Let us look att each of these three.


ORDBMS, – DB2 Relational Extenders

The first IBM attempt to implement SQL3 was in DB2 version 5, where UDTs,UDFs, LOBs, triggers and stored procedures were introduced, some of them withIBM specific notation.

In version 6 they introduced abstract data types and extendibility as described onthe pervious slide.With the system you get four Relational extenders that can be used to create newextenders.


ORDBMS, – DB2 Relational Extenders . . .

Using the attached relstonal extenders, UDTs, UDFs, et.c. the DBA can createnew extenders that cover any data storage need.

Third party relational extender developers use exactly the same tools.

All collected knowledge about RDBMS is still relevant.

Nowadays many third party relational extenders are available.

They are simple to install and activate.

Once plugged in and activated they act as a fully integral part of the DBMS


ORDBMS, – DB2 Relational Extenders . . .


ORDBMS, – Informix DataBladesSimilarily an Informix DataBlade is a standard software module that can beplugged in to their DBMS.A datablade contains

• one ADT,

• any number of ADF,

• access methodes,

• indexing methods,

• optimizing methods,

• functions to manipulate the type of data that is defined in the datablade,

• rule definitions and

• restrictions that, once defined, allows the DBMS to cheack them the same way as anybuilt-in restrictions


ORDBMS, – Informix DataBlades . . .

In Informix Dynamic Server (earlier universal server) all values, including thosethat are generated from an ADT are first class valuesand may be

• stored,

• inspected (you may query all parts),

• indexed,

• sent to application programs,

• sent as function parameters

et.c.

and they may be defined in terms of already existing ADTs and/or predefinedtypes.



There are three basic ADTs in datablades:• row-types• distinct types• “opaque types” – that may be implemented in C, C++ or Java. With “opaque”

is meant that you cannot “look into” them. They are not part of theinspectable values.



A UDF can be programmed in Informix Stored Procedure Language (SPL), C,C++, or Java.

Those that are programemd in C, C++, or Java are compiled and stored in ashared object file or a DDL and when the function is invoked, the object code islinked into the running program and executed in the server runtime memory.

You may store your own runtime modules for each language in the DBMS in orderto ensure that you use the appropriate runtime for each used language (theruntime against which compilation was performed)



You may implement your set of access methods, which is essentially a set offunctions to

• start index scanning

• get the next tuple

• insert a tuple

• delete a tuple

This, turn means that you may design and install specialized indexes like R-treesto manage spatial data types.



There is even an API that allows databalades to use other datablades.

Datablades may be stored in the database (of course) and they may manipulaetheir own definition (reflection ??).

This makes them data driven and simple to change, manage and . . . extend.

There is a development kit for datablade developers.




ORDBMS, – Oracle Cartridges

Oracle Cartridge is a key component in Oracle Network Computing Architecture(NCA).

The other components are• client applications,

• Oracle Universal Application Server and

• Oracle Universal Server.

All communicate using open standard protocols internally and externally


ORDBMS, – Oracle Cartridges . . .

From a DB view Oracle Universal Server that provides extedible, scalable datastorage facilities.

A cartridge is a pluggable module that may be manipulated by other software

Its internal structure is defined in standard SQL3 and its interface uses the IMGIDL (as CORBA does)

You may use C, C++, PL/SQL or Java when developing cartridges.

In the NCA architecture there are three kinds of cartridges (the classificationshows their expected location in the NCA architecture)



• A data cartridge is managed in the DBMS and can access Oracles extensibledatabase services.

• An application server cartridge may be managed either by the applicationserver or in the database server depending on hos tightly application logicsare tied to data stored in DB. In the last version of Oracle that I looked intothey were stored in the application server and communicated with DBMS viaCORBA/IIOP.

• A client cartrig runs on the client side using the usual standard API:s.



Cartridge-objects communicate via a special internal bus, the Inter-CartridgeExchange (ICX).

The ICX is implemented as a set of libraries and services that enable all theinternal programs, in a set of programs that together form an application, to quitefreely communicate with each others and surrounding servers and services.

The ICX uses HTTP and IIOP for communication and performs automaticallycertain conversions if necessary.

The ICX has an API to manage contact with ActiveX, Java (using CORBA/IDL –IIOP – JDBC), and a large number of programming languages and applicationprograms on the market.




Finally

The brains behind most of the ideas in the ORDBMS world is the team, headed byMichael Stonebraker, that created Ingres, Postgres, Illustra and, finally, theInformix Dynamic Server.

The three big dragons – IBM, Informix and Oracle – have seen success but in siteof all the similarities there are differences

DB2 (supposedly) builds on conformance with the SQL3 standard, Oracle on theuse of open standards for communication, mainly IDL and CORBA while Informixhas focused on the hardships with adding non-relational stuff in a relationalsystem and the difficulty to mold them into the system and therefore deliverspowerful tools for developing datablades and to install them into the system(BladeSmith, Bladepack och Blademanager)


Some other systems

AMOS II (Uppsala University Database laboratory)Cache (InterSystems)Data Access FrameWork / Total (CinCom)Enterprise Application Server (Sybase)KE Texpress (Knowledge Engineering)JBMS (Cloudscape)Lincks (Linkoping University)Matisse (Matisse)Microsoft Repository (Microsoft)ODB-II (Fujitsu)OSMOS (Unisys)Phasme DBMS (Frederic Andres)Polyhedra (Polyhedra)PostgreSQL (UCB)UniSQL (Cincom)


Documents

SQL3 / SQL:2008 - KTH · SQL3 / SQL:2008 The SQL3 standard is big and is therefore divided into parts: 1.SQL/Framework, contains information common to all parts of the standard