SQLJ: Java and Relational Databases

1
SQLJJava and Relational Databases

• Phil Shaw, Sybase Inc.
• Brian Becker, Oracle Corp.
• Johannes Klein, Tandem/Compaq
• Mark Hapner, JavaSoft
• Gray Clossman, Oracle Corp.
• Richard Pledereder, Sybase Inc.

2
Agenda

• Introduction
• SQLJ Part 0 Embedded SQL and Portability Profile
• SQLJ Part 1 Java Methods as SQL Procedures
• SQLJ Part 2 Java Classes as SQL Types

3
Java and Databases

• JDBC
• Java Database Connectivity API
• Widely Implemented
• SQLJ
• Java-Relational Database Technology
• Portability Productivity Java in the Database
• Leverages JDBC technology
• JavaBlend
• Object/Relational Mapping for Java
• The focus of this tutorial is on SQLJ

4
SQLJ - The Consortium

• Structure is informal
• Participants include Oracle, IBM, Sybase, Tandem,
  JavaSoft, Microsoft, Informix, XDB
• Open to other participants
• Meetings
• Approximately every 3-4 weeks
• Hosted by one of the Bay Area resident vendors
  (Oracle, Sybase, Tandem, JavaSoft, Informix,
  etc.)
• Participants Product Architects SQL Standards
  people

5
SQLJ - The Technology

• Part 0 SQLJ Embeded SQL
• Mostly reviewed and implemented
• Integrated with JDBC API
• Oracle has placed Translator source into public
  domain
• Part 1 SQLJ Stored Procedures and UDFs
• Using Java static methods as SQL stored
  procedures functions
• Leverages JDBC API
• Part 2 SQLJ Data Types
• Pure Java Classes as SQL ADTs
• Alternative to SQL3 Abstract Data Types

6
SQLJ - The Standard

• Goal of the SQLJ Consortium is to create workable
  standards specifications in web time
• The Consortium is working with ANSI X3H2 on a
  fast-track process for adopting SQLJ as a
  standard
• The Consortium also works with The Open Group on
  a set of conformance tests

7
SQLJ - Implementation Status

• SQLJ Embedded SQL
• Public-domain reference implementation available
  from Oraclehttp//www.oracle.com/st/products/jdbc
  /sqlj
• Profile customizations available from Oracle,
  IBM, Sybase, Tandem,
• SQLJ Procedures
• Specifications mostly reviewed
• Implementations, e.g., Sybase Adaptive Server
  Anywhere 6.0, Oracle 8.1, IBM
• SQLJ Data Types
• Specifications through first pass
• Implementations, e.g., Sybase Adaptive Server
  Anywhere 6.0

8
JDBC 2.0 - SQLJ Features

• Support for user-defined, object data types
• Java Classes
• Persistent Java objects stored in the DBMS
• SQL3 types
• BLOB, CLOB, array, reference
• Structured and distinct types
• New type codes
• JAVA_OBJECT, STRUCT, BLOB, etc.
• Metadata for user-defined types
• int types Types.JAVA_OBJECT
• ResultSet rs dmd.getUDTs("catalog-name",
  "schema-name", "", types)

9
JDBC 2.0 - SQLJ Features

• Objects-by-Value
• Java Classes as database types
• this just works
• SQL3 ADTs as database types
• Java mapping maintained per Connection
• Seamless extension of get/setObject()
• Statement stmt
• ResultSet rs stmt.executeQuery(
• "SELECT CUSTOMER FROM ACCOUNTS")
• rs.next()
• Customer cust (Customer)rs.getObject(1)

10
Agenda

• Overview and JDBC 2.0 New Features
• SQLJ Part 0 Embedded SQL and Portability Profile
• SQLJ Part 1 Java Methods as SQL Procedures
• SQLJ Part 2 Java Classes as SQL Types

11
SQLJ Part 0SQL Embedded in Java

• Objectives
• Simple, concise language for embedding SQL
  statements in Java programs
• Standard to allow for assembly of binary
  components produced by different tools
• Standard to allow for binary portability across
  different database systems

12
Advantages

• Ahead-of-time syntax and type checking
• Strongly typed cursors (iterators)
• Offline pre-compilation (for performance)
• Deployment-time customization (for binary
  portability and native pre-compilation)

13
SQLJ clauses

• SQLJ statements start with sql
• SQLJ statements terminate with
• SQLJ host variables start with
• SQL text is enclosed in curly braces ..int
  nsql INSERT INTO emp VALUES (n)
  

14
SQLJ more concise than JDBC
// SQLJ int n sql INSERT INTO emp VALUES
(n) // JDBC int n Statement stmt
conn.prepareStatement (INSERT
INTO emp VALUES (?)) stmt.setInt(1,n) stmt.exec
ute () stmt.close()
15
Strongly typed cursors

• Positional binding to columns

sql public iterator ByPos (String, int)ByPos
positerString name nullint year 0 sql
positer SELECT name, year FROM peoplewhile
(true) sql FETCH positer INTO name,
year if (positer.endFetch()) break
// process name, year positer.close()
16
Strongly typed cursors (cont.)

• Named binding to columns

sql public iterator ByName (int year, String
name) ByName namiterString name nullint
year 0 sql namiter SELECT name, year
FROM peoplewhile (namiter.next()) name
namiter.name() year namiter.year() //
process name, year namiter.close()
17
Connection context

• SQLJ statements are associated with a connection
  context
• Context type identifies exemplar schema, e.g.
  views, tables, privilegessql context
  DepartmentDepartment dept newDepartment(jdbc
  odbcacme.cs)int nsql dept insert into
  EMP values (n)

18
Extensible SQLJ framework

• Database vendors plug-in SQL syntax checkers and
  semantic analyzers using SQLChecker framework
• Database vendors provide customizers to install
  SQLJ binaries (profiles) in target database
• Default SQLJ binaries run on any JDBC driver

19
SQLJ translator framework
Java Class Files
SQLChecker
SQLChecker
SQLJ program
Java Frontend
SQLJ Customizations
Profile Customizer Utility
SQLJ Profiles
SQLJ Translator
SQLJ JAR FILE
20
SQLJ portability layers
SQLJ Program
Profile Entries
JDBC
SQL DB
SQL DB
SQL DB
21
Custom SQL execution
SQLJ Program
Profile Entries
JDBC
Customizations
Stored procedure
TP service
SQL Module
SQL DB
SQL DB
SQL DB
22
Profile customization selection
Customizations
Profile
Data source URLs
23
SQLJ profile objects
Profile
ProfileData
EntryInfo
TypeInfo
ConnectedProfile
Customization
RTStatement
24
SQLJ compilation phases
Foo.sqlj
Foo.java
Foo.class
25
SQLJ translation phase
Foo.sqlj
26
SQLJ semantic analysis
Foo.sqlj
Ctx0SQL0
27
SQLJ semantic analysis
Foo.sqlj
Ctx0SQL0
Ctx0SQL1
describe(SQL1)
SQLChecker0
28
SQLJ semantic analysis
Foo.sqlj
Ctx0SQL0
Ctx0SQL1
(Ctx1)SQL2
29
SQLJ code generation
Foo.sqlj
Foo.java
Ctx0SQL0
Ctx0SQL1
Ctx1SQL2
30
SQLJ code generation
Foo.jsql
Foo.java
Ctx0SQL0
Profile0Entry0
Ctx0SQL1
Ctx1)SQL2
Profile0.ser
Entry0
31
SQLJ code generation
Foo.jsql
Foo.java
Ctx0SQL0
Profile0Entry0
Ctx0SQL1
Profile0Entry1
Ctx1SQL2
Profile0.ser
Entry0
Entry1
32
SQLJ code generation
Foo.jsql
Foo.java
Ctx0SQL0
Profile0Entry0
Ctx0SQL1
Profile0Entry1
Ctx1SQL2
Profile1Entry0
Profile0.ser
Entry0
Entry1
Profile1.ser
Entry0
33
Java compilation
Foo.sqlj
Foo.java
Foo.class
Ctx0SQL0
Profile0Entry0
Profile0Entry0
Java Compiler
Ctx0SQL1
Profile0Entry1
Profile0Entry1
Ctx1SQL2
Profile1Entry0
Profile1Entry0
Profile0.ser
Entry0
Entry1
Profile1.ser
Entry0
34
SQLJ packaging
Foo.jar
Foo.sqlj
Foo.java
Foo.class
Ctx0SQL0
Profile0Entry0
Profile0Entry0
Java Compiler
Ctx0SQL1
Profile0Entry1
Profile0Entry1
Ctx1SQL2
Profile1Entry0
Profile1Entry0
Profile0.ser
Entry0
Entry1
Profile1.ser
Entry0
35
SQLJ installation phase
36
SQLJ installation phase
Foo.jar
Foo.class
Profile0.ser
Customization
Profile1.ser
37
SQLJ installation phase
Foo.jar
Foo.jar
Foo.class
Foo.class
Customizer2
Profile0.ser
Profile0.ser
Customization1
Customization1
Customization2
Profile1.ser
Profile1.ser
Customization2
38
Agenda

• JDBC 2.0 New Features
• SQLJ Part 0 Embedded SQL and Portability Profile
• SQLJ Part 1 Java Methods as SQL Procedures
• SQLJ Part 2 Java Classes as SQL Types

39
SQLJ Part 1Java methods as SQL procedures

• Use Java static methods as SQL stored procedures
  and functions.
• Advantage to SQL Direct use of pre-written Java
  libraries.
• A procedural and scripting language for SQL.
• Portable across DBMSs.
• Deployable across tiers.

40
Technical objectives

• Convenient for Java programmers.
• Not just aimed at SQL programmers.
• Portable across DBMSs.
• Same capability as regular SQL stored procedures.
• Arbitrary SQL stored procedures re-codable as
  SQLJ stored procedures.
• Convenience and performance comparable with SQL
  routines.
• Callable from CLI/ODBC, from other SQL stored
  procedures, from JDBC/JSQL, and directly from
  Java.
• Caller needn't know the SQLJ stored procedure is
  in Java.

41
Technical objectives (cont.)

• Any Java static method callable as a stored
  procedure
• Initially support only parameter and result types
  mappable to SQL.
• Extensible to support arbitrary Java types, for
  Java caller and callee.
• Body of SQLJ stored procedure routines can use
  JDBC and/or SQLJ to access SQL, or Java
  computation
• Initially support persistence only for duration
  of a call.
• Consider session and database persistence as
  follow-on.

42
Topics

• Example Java classes
• Defining Java classes to SQL
• Installing jar files
• Specifying SQL names
• SQL Permissions
• OUT parameters
• Result sets
• Error handling
• Paths
• Deployment descriptors

43
Examples

• Example table
• create table emps (
• name varchar(50),
• id char(5),
• state char(20),
• sales decimal (6,2))
• Example classes and methods
• Routines1.region Maps a state code to a region
  number. Plain Java (no SQL).
• Routines1.correctStates Performs an SQL update
  to correct the state codes.
• Routines2.bestEmpsReturns the top two employees
  as output parameters.
• Routines3.rankedEmpsReturns the employees as a
  result set.

44
Examples (cont.)

• The region and correctStates methods
• public class Routines1
• //The region method
• //An Integer method that will be called as a
  function
• public static Integer region(String s) throws
  SQLException
• if (s "MN" s "VT" s "NH" )
  return 1
• else if (s "FL" s "GA" s "AL" )
  return 2
• else if (s "CA" s "AZ" s "NV")
  return 3
• else return 4
• //The correctStates method
• //A void method that will be called as a stored
  procedure
• public static void correctStates (String
  oldSpelling, String newSpelling) throws
  SQLException
• Connection conn DriverManager.getConnection
  ("JDBCDEFAULTCONNECTION")
• PreparedStatement stmt conn.prepareStatement
  ("UPDATE emps SET state ? WHERE state ?")
• stmt.setString(1, newSpelling)
• stmt.setString(2, oldSpelling)
• stmt.executeUpdate()
• return

45
Installing Java Classes in SQL

• New install_jar procedure
• sqlj.install_jar ('file/classes/Routines1.jar',
  'routines1_jar' )
• Two parameters
• The URL of a jar file containing a set of Java
  classes
• A character string that will be used to identify
  the Jar in SQL
• Installs all classes in the jar file
• Uses Java reflection to determine their names,
  methods, and signatures
• Retains the Jar file, the character string
  identifies it
• The jar name is specified in a later remove_jar
  procedure
• Follow-on facilities will address replacing and
  downloading jar files, etc.

46
Defining SQL names for Java methods

• A form of the SQL create procedure/function
  statement.
• create procedure correct_states(old char(20), new
  char(20))
• modifies sql data
• external name 'routines1_jarRoutines1.correctStat
  es'
• language java parameter style java
• create function region_of(state char(20)) returns
  integer
• no sql
• external name 'routines1_jarRoutines1.region'
• language java parameter style java
• The create procedure statement and the external
  language X are standard.
• The language alternative java is an SQLJ
  extension.

47
Defining SQL names for Java methods

• The procedure/function names "correct_states" and
  "region_of" are normal SQL 3-part names, with
  normal defaults.
• You can do multiple create procedure statements
  pointing to the same Java method.
• The key role of create procedure is to define an
  SQL synonym for the Java method.
• Why use an SQL name?
• Java names have different syntax
  case-sensitive, package names, Unicode, etc.
• SQL metadata and permissions are keyed to SQL
  names.

48
Privileges

• The usage privilege on the installed jar file is
  grantable
• grant usage on routines1_jar to Smith
• The execute permission on the SQL names is
  grantable.
• grant execute on correct_states to Smith
• Methods run with "definer's rights".

49
Invoking Java methods

• Use the SQL names, with normal defaults for the
  first two parts
• select name, region_of(state) as region
• from emps
• where region_of(state) 3
• call correct_states ('CAL', 'CA')

50
OUT parameters

• SQL procedures have OUT and INOUT parameters
  Java doesn't.
• If a Java method will be used as an SQL proc with
  OUT parameters, those parameters are declared as
  Java arrays, to act as "containers".
• Example (next page)
• bestTwoEmps returns the two top employees in a
  given region.
• The specific region is an in parameter.
• The column values of the two top employees are
  out parameters.
• The bestTwoEmps method is coded with JSQL.
• A version of bestTwoEmps coded with JDBC is shown
  in the draft specs, for comparison.

51
OUT Parameters (cont.)

• public class Routines2
• public static void bestTwoEmps (String n1,
  String id1, int r1, BigDecimal s1,
• String n2, String id2, int r2,
  BigDecimal s2,
• Integer regionParm) throws SQLException
• sql iterator ByNames (String name, int id, int
  region, BigDecimal sales)
• ByNames r
• sql r "SELECT name, id, region_of(state) as
  region, sales FROM emp
• WHERE region_of(state) gt
  regionParm AND sales IS NOT NULL
• ORDER BY sales DESC"
• if (r.next())
• n10 r.name() id10 r.id()
• r10 r.region() s10 r.sales()
• else n10 "" return
• if (r.next())
• n20 r.name() id20 r.id()
• r20 r.region() s20 r.sales()
• else n20 "" return

52
OUT parameters (cont.)

• CREATE PROC for the bestTwoEmps method
• The bestTwoEmps method has eight out parameters
  and one in parameter
• create procedure best2
• (out n1 varchar(50), out id1 varchar(5), out r1
  integer, out s1 decimal(6,2),
• out n2 varchar(50), out id2 varchar(5), out r2
  integer, out s2 decimal(6,2),
• region integer)
• reads sql data
• external name 'Routines2.bestTwoEmps'
• language java parameter style java

53
OUT parameters (cont.)

• Invoking the best2 procedure
• java.sql.CallableStatement stmt
  conn.prepareCall ("call best2(?,?,?,?,?,?,?,?,?)
  ")
• stmt.registerOutParameter(1, java.sql.Types.String
  )
• stmt.registerOutParameter(2, java.sql.Types.String
  )
• stmt.registerOutParameter(3, java.sql.Types.Int)
• stmt.registerOutParameter(4, java.sql.Types.BigDec
  imal)
• stmt.registerOutParameter(5, java.sql.Types.String
  )
• stmt.registerOutParameter(6, java.sql.Types.String
  )
• stmt.registerOutParameter(7, java.sql.Types.Int)
• stmt.registerOutParameter(8, java.sql.Types.BigDec
  imal)
• stmt.setInt(9, 3)
• stmt.executeUpdate()
• String n1 stmt.getString(1)
• String id1 stmt.getString(2)
• Integer r1 stmt.getInt(3)
• BigDecimal s1 stmt.getBigDecimal(4)
• String n2 stmt.getString(5)
• String id2 stmt.getString(6)

54
Result sets

• SQL procedures can return result sets that are
  neither parameters nor function results.
• An SQL result set is a set of rows generated by
  the callee for the caller. The caller processes
  the result set iteratively.
• SQLJ models this as follows
• An SQL3 clause on create procedure specifies that
  the proc has result sets.
• Such an SQL proc can be defined on a Java method
  with a result set return value.
• Example (below)
• The orderedEmps method returns a result set with
  the employees of a given region ordered by sales.

55
Result sets (cont.)

• Example The orderedEmps method
• public class Routines3
• public static orderedEmps(int regionParm,
  ResultSet rs )
• throws SQLException
• Connection conn DriverManager.getConnection
• ("JDBCDEFAULTCONNECTION")
• java.sql.PreparedStatement stmt
  conn.prepareStatement
• ("SELECT name, region_of(state) as region, sales
  
• FROM emp WHERE region_of(state) gt ?
• AND sales IS NOT NULL
• ORDER BY sales DESC")
• stmt.setInteger(1, regionParm)
• rs0 stmt.executeQuery()
• return

56
Result sets (cont.)

• CREATE PROC for the orderedEmps method
• The orderedEmps method returns one result set
• create procedure ranked_emps (region integer)
• dynamic result sets 1
• reads sql data
• external name 'Routines3.orderedEmps'
• language java parameter style java
• The dynamic result sets clause is standard
  ISO/ANSI SQL3.
• Initially the dynamic result sets clause will
  only allow "1".

57
Result sets (cont.)

• Invoking the rankedEmps procedure
• java.sql.CallableStatement stmt
  conn.prepareCall(
• "call ranked_Emps(?)")
• stmt.setInt(1, 3)
• ResultSet rs stmt.executeQuery()
• while (rs.next())
• String name rs.getString(1)
• Integer region rs.getInt(2)
• BigDecimal sales rs.getBigDecimal(3)
• System.out.print(" Name " name)
• System.out.print(" Region " region)
• System.out.print(" Sales " sales)
• System.out.print("\n")

58
Error Handling

• General treatment
• Exceptions thrown and caught within an SQLJ
  stored procedure are internal to Java.
• Exceptions that are uncaught when you return from
  a Java method become SQLSTATE error codes.
• The message text of the SQLSTATE is the string
  specified in the Java throw.

59
Paths

• In Java, resolution of class names is done with
  the operating system CLASSPATH.
• The CLASSPATH mechanism uses the operating system
  directory structure.
• SQLJ defines a similar mechanism for name
  resolution.
• Assume you have three jar files that reference
  classes in each other
• The admin jar references classes in the
  property and project jars.
• The property jar references classes in the
  project jar.
• The project jar references classes in the
  property and admin jars.

60
Paths (cont.)

• You install the jar files as usual
• sqlj.install_jar (file/classes/admin.jar,
  admin_jar)
• sqlj.install_jar (file/classes/property.jar,
  property_jar)
• sqlj.install_jar (file/classes/project.jar,
  project_jar)
• Then you specify paths for the jar files
• sqlj.alter_java_path (admin_jar, (property/,
  property_jar) (project/, project_jar))
• sqlj.alter_java_path (property_jar,
  (project/, project_jar ))
• sqlj.alter_java_path (project_jar, (,
  property_jar) (, admin_jar) )
• When the Java VM encounteres an unloaded class
  name in e.g. the admin_jar, it will invoke the
  class loader supplied by the SQL system, which
  will use the SQL path to resolve the name.

61
Deployment descriptors

• A deployment descriptor is a text file containing
  the create and grant statements to do on
  install_jar, and the drop and revoke statements
  to do on remove_jar.
• A deployment descriptor is contained in a jar
  file with the classes it describes.
• The install_jar procedure will implicitly perform
  the create and grant statements indicated by the
  deployment descriptor.
• The remove_jar procedure will implicitly perform
  the drop and revoke statements indicated by the
  deployment descriptor.

62
Deployment descriptors (cont.)

• Example deployment descriptor
• Assume that all of the above example classes
  Routines1, Routines2, and Routines3 are in a
  single jar.
• An example deployment descriptor for that jar
  would have the following form
• SQLActions
• BEGIN INSTALL
• // SQL create and grant statements
• // to be executed when the jar is installed.
• END INSTALL ,
• BEGIN REMOVE
• //SQL drop and revoke statements
• // to be executed when the jar is removed.
• END REMOVE

63
Agenda

• Introduction
• SQLJ Part 0 Embedded SQL and Portability Profile
• SQLJ Part 1 Java Methods as SQL Procedures
• SQLJ Part 2 Java Classes as SQL Types

64
SQLJ Part 2 Java classes as SQL types

• Use Java classes as SQL data types for
• Columns of SQL tables and views.
• Parameters of SQL routines.
• Especially SQL routines defined on Java methods
  (SQLJPart 1).
• Advantage to SQL
• A type extension mechanism.
• Either an alternative or supplement to SQL3 ADTs.
• Advantage to Java
• Direct support for Java objects in SQL databases.
• No need to map Java objects to SQL scalar or BLOB
  types.

65
Examples

• Example class Address
• public class Address implements
  java.io.Serializable
• public String street
• public String zip
• public static int recommended_width 25
• // A default constructor
• public Address ( )
• street "Unknown"
• zip "None"
• // A constructor with parameters
• public Address (String S, String Z)
• street S
• zip Z
• // A method to return a string representation of
  the full address
• public String toString( )
• return "Street " street " ZIP " zip

66
Examples (cont.)

• Example subclass Address2Line
• public class Address2Line extends Address
  implements java.io.Serializable
• public String line2
• // A default constructor
• public Address2Line ( )
• line2 " "
• // A constructor with parameters
• public Address2Line (String S, String L2, String
  Z)
• street S
• line2 L2
• zip Z
• // A method to return a string representation of
  the full address
• public String toString( )
• return "Street " street " Line2 " line2
  " ZIP " zip

67
CREATE TYPE

• The role of create type is like that of create
  procedure
• Specify SQL names for the type, the fields, and
  the methods.
• Additional clauses for ordering specs, etc.
• The above example uses the default ordering

68
CREATE TYPE (cont.)

• CREATE for Address
• create type addr
• external name 'Address' language java
• (zip_attr char(10) external name 'zip',
• street_attr varchar(50) external name 'street',
• static rec_width_attr integer external name
  'recommended_width',
• method addr ( ) returns addr external name
  'Address',
• method addr (s_parm varchar(50), z_parm char(10))
  returns addr
• external name 'Address',
• method to_string ( ) returns varchar(255)
  external name toString,
• method remove_leading_blanks ( ) external name
  removeLeadingBlanks
• static method contiguous (A1 addr, A2 addr)
  returns char(3)
• external name 'contiguous'
• )

69
CREATE TYPE (cont.)

• CREATE for Address2
• create type addr_2_line
• under addr
• external name 'Address2Line' language java
• (line2_attr varchar(100) external name 'line2',
• method addr_2_line ( ) returns addr_2_line
  external name 'Address2Line',
• method addr_2_line (s_parm varchar(50), s2_parm
  char(100), z_parm char(10))
• returns addr_2_line external name
  'Address2Line',
• method to_string ( ) returns varchar(255)
  external name 'toString',
• method remove_leading_blanks ( ) external name
  removeLeadingBlanks
• method strip ( ) external name 'removeLeadingBlank
  s'
• )

70
Usage Privilege

• GRANTs for Address and Address2Line
• grant usage on datatype addr to public
• grant usage on datatype addr2line to admin

71
Java Classes as SQL datatypes

• Column data types
• create table emps (
• name varchar(30),
• home_addr addr),
• mailing_addr addr_2_line)
• Insert
• insert into emps values('Bob Smith', new
  Address('432 Elm Street', '99782'),
• new Address2Line('PO Box 99', 'attn Bob Smith',
  '99678'))
• Select
• select name, home_addrgtgtzip, home_addrgtgtstreet,
  mailing_addrgtgtzip
• from emps
• where home_addrgtgtzip ltgt mailing_addrgtgtzip
• Methods and comparison
• select name, home_addrgtgtdisplay(),
  mailing_addrgtgtdisplay()
• from emps
• where home_addr ltgt mailing_addr

72
Java Classes as SQL datatypes (cont.)

• Update
• update emps
• set home_addrgtgtzip '99783'
• where name 'Bob Smith'
• update emps
• set home_address mailing_address --Normal
  Java substitutability
• where home_address is null
• Note the use of gtgt to reference fields and
  methods of Java instances in SQL.
• This avoids ambiguities with SQL dot-qualified
  names.
• The gtgt symbol is used in SQL3 for ADT
  references.

73
SQLJJava and Relational Databases

• Phil Shaw, Sybase Inc.
• Brian Becker, Oracle Corp.
• Johannes Klein, Tandem/Compaq
• Mark Hapner, JavaSoft
• Gray Clossman, Oracle Corp.
• Richard Pledereder, Sybase Inc.