F15
Fundamentals of DB2 SQL Procedures
Philip K. Gunning, DGI
Anaheim, CA
Sept 9 - 13, 2002
IBM Corporation 2002
Outline
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Background
Installation and Preparation
Setup
Development Center (SPB, et al)
Building SQL Procedures
Case Study
Performance Considerations
Summary
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Background
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Background
• First appeared in DB2 UDB V7.1
– DB2 for OS/390 V6.1
• Other Database Vendors have had their own
proprietary stored procedure languages for
some time
• Search on YAHOO! found 78,000 hits on
“Oracle Stored Procedures”
• Search on YAHOO! Found 31,600 hits on
“Sybase Stored Procedures”
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Background
• Search on YAHOO! Found 25,200 hits on
“DB2 Stored Procedures”
• Search on YAHOO! Found 44,500 hits on
“Transact SQL”
• Search on YAHOO! Found 11 hits on
“PL/SQL”
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Background
• Many applications have been written in
their entirety in a stored procedure language
– Flexibility
– Enable Rapid Application Development
– Minor learning curve since similar to SQL
• Portability Across Platforms
– Cross Platform Development and Debugging
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Installation and Preparation
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Installation and Preparation
• UNIX
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Application Development Client
AIX V4.3.3 ML9 or 5.1 ML1
IBM C for AIX Version 5.0
IBM Visual Age C++ Version 5.0
• Windows XP, .NET, 2000, NT, ME, 98
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Installation and Preparation
• Change DBM CFG Parameter
KEEPFENCED (KEEPDARI) to NO while
developing and testing routines
– If not, changes will not be reloaded as process
that runs the routine will remain active
• db2 update dbm cfg using KEEPFENCED
no
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Installation and Preparation
• UNIX
– Set two registry values
– DB2_SQLROUTINE_COMPILER_PATH
– DB2_SQLROUTINE_COMPILE_COMMAND
– PATH and LIBPATH environment variables set in
db2profile and call to it is placed in .profile
• Can either use the db2set cmd or use the SQL Stored Procedure
Builder Options dialog form the Development Center to set the values
of these DB2 registry variables
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Installation and Preparation
• Windows
– Application Development Client
– SQL Procedures supported on NT, 2000, XP and
.NET Server
– DB2_SQLROUTINE_COMPILER_PATH
– DB2_SQLROUTINE_COMPILE_COMMAND
• Need not be set if environment variables for
compiler set as SYSTEM variables
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Installation and Preparation
• MVS Conformance Flagger
– Used to Flag SQL for procedures developed on
workstation which are being migrated to DB2
for OS/390 or Z/OS
– ISO/ANSI SQL92 Entry Level Standard
• http://www7b.boulder.ibm.com/dmdd/librar
y/techarticle/0204milligan/0204milligan.ht
ml
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Installation and Preparation
• Management Tools FMID required for DB2
for Z/OS or OS/390
– REXX Support for DSNTPSMP SP Creation
– C compiler
– Workload Manager and appropriate WLM
application environments
– DB2 V6.1 and above
• SQL Reference for Cross Platform
Development
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Installation and Preparation
• Recoverable Resource Manager Services
attachment facility (RRSAF) required on
Z/OS
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SQL
• Procedure created via CREATE
PROCEDURE COMMAND
• CREATE PROCEDURE update_salary (
IN employee_number CHAR(6),
IN rating INT )
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Attendee Notes
 Create procedure may fail in the precompile or compile stage. DB2 will create
a log file that contains error messages. This log will be placed in the
/sqlproc/db_name/schema_name/tmp or \sqlproc\db_name\schema_name\tmp
directory on Windows.
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SQL
• SQL-Procedure Body keyword of CREATE
PROCEDURE statement specifies the SQL
statement that is the body of the SQL
Procedure
• Multiple SQL Procedure statements can be
specified within a compound statement
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SQL
CREATE PROCEDURE bump_salary (IN deptnumber SMALLINT)
LANGUAGE SQL
BEGIN
DECLARE SQLSTATE CHAR(5);
DECLARE v_salary DOUBLE;
DECLARE v_id SMALLINT;
DECLARE v_years SMALLINT;
DECLARE at_end INT DEFAULT 0;
DECLARE not_found CONDITION FOR SQLSTATE '02000';
DECLARE C1 CURSOR FOR
SELECT id, CAST(salary AS DOUBLE), years
FROM staff
WHERE dept = deptnumber;
DECLARE CONTINUE HANDLER FOR not_found
SET at_end = 1;
Copyright IBM Corp. Sample Procedure
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OPEN C1;
FETCH C1 INTO v_id, v_salary, v_years;
WHILE at_end = 0 DO
CASE
WHEN (v_salary < 2000 * v_years)
THEN UPDATE staff
SET salary = 2150 * v_years
WHERE id = v_id;
WHEN (v_salary < 5000 * v_years)
THEN CASE
WHEN (v_salary < 3000 * v_years)
THEN UPDATE staff
SET salary = 3000 * v_years
WHERE id = v_id;
ELSE UPDATE staff
SET salary = v_salary * 1.10
WHERE id = v_id;
END CASE;
ELSE UPDATE staff
SET job = 'PREZ'
WHERE id = v_id;
END CASE;
FETCH C1 INTO v_id, v_salary, v_years;
END WHILE;
CLOSE C1;
END @
Copyright IBM Corp. Sample Procedure
SQL
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Attendee Notes
 The procedure body consists of a procedure-name, that names the procedure
being defined. In dynamic SQL, CURRENT SCHEMA is used as a qualifier
for an unqualified name and the QUALIFIER bind option for static SQL. The
unqualified name with the number of parameters is unique within its schema,
but does not need to be unique across schemas. This is know as overloading in
other languages. IN, OUT, or INOUT identifies the parameters of the
procedure and specifies the mode, name and data type of each parameter.
 Specific-name is used for commenting on or dropping the procedure. It can
never be used to invoke the procedure.
 Dynamic results is an upper bound for returned result sets.
 Contains, Reads, and Modifies SQL DATA
 LANGUAGE SQL FOR SQL PROCEDURES
 SQL PROCEDURE BODY specifies the SQL statement that is the body of
the SQL procedure.
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SQL
• CALL statement invokes stored procedure
– Has a procedure signature which is a
combination of schema, procedure name and
number of parameters
• Returning Result Sets
– Declare cursor on result set, open result set, and
leave cursor open when exiting procedure
– only unread rows are passed back
– use nulls to improve performance
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SQL
• If result sets are required then RETURN to
CALLER or RETURN TO CLIENT must
be specified
– RETURN TO CALLER results are only visible
to program at previous nesting level
– RETURN TO CLIENT results are visible only
if procedure was invoked from a set of nested
procedures, function or method invalidates this
– Only visible to client application that made the
call
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SQL
• See Appendix N, DB2 UDB SQL Reference
for complete list of SQL statements allowed
in SQL routines
• See DB2 for Z/OS SQL Reference for that
platform
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SQL
• Condition Handlers
– Control passed to condition handler if a
condition is raised and you have declared a
handler for the respective condition
– If no handler, DB2 passes control to next
statement in procedure body
• SQLCODE and SQLSTATE will contain
corresponding values if they were declared
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Attendee Notes
 If a statement raises an SQLWARNING or NOTFOUND condition, DB2
passes control to the handler you declared. If a statement raises an
SQLEXCEPTION condition control is passed to the handler for that specific
condition.
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SQL
• SIGNAL and RESIGNAL Statements
– can be used to explicitly raise a specific
SQLSTATE
• CALL is now a compiled statement and can
be run from a command line
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Development Tools
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Development Center
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Stored Procedure Builder
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SQL Procedure
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SQL Procedure
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SQL Procedure
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Deploy
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Deploy
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Case Study
• Texas Department of Public Safety
• Combined 8 legacy applications into 1
using all SQL Procedures
• Started out on DB2 UDB V7.1
– JAVA Stored Procedures
– Got proficient with SPB and development on
Windows
• Migrated to DB2 for OS/390 V6.1
• Switched to SQL Procedures
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Case Study
• Developed concurrently on DB2 for
Windows whilst connectivity to OS/390 was
being established
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TCP/IP
DDF
CICS
Workload Manager (WLM)
WLM Stored Procedures
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Case Study
• After DB2 V6.1 and OS/390 configured
developed over 300 SQL Procedures
• Implemented Texas Crime Information
Center application totally in SQL
Procedures
• Credited flexibility and ease of development
in streamlining the typical development
timeline
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Case Study
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•
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Used DB2 Management Clients package
DB2 Control Center
DB2 Stored Procedure Builder
DB2 Visual Explain
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Case Study
• Still did good Logical and Physical Design
• Extensive use of Identity Columns
• Developed good indexes via DB2 Explain
and SQL Reviews
• Attaining sub-second response
• Continue to add new features/functionality
using SQL Procedures
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Case Study
• Lessons Learned
– Want to be leading-edge but not necessarily
bleeding-edge!
– Lot’s of time spent getting TCP/IP, DB2 for
OS/390 V6.1, DSNTSMP stored procedure
working along with WLM
– Ran into 32k limitation and had to use multiple
stored procedures
– Starting/Stopping/Purging WLM procedures
took some time to develop
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References
 SC09-4848-00, What’s New, V8.1
 DB2 UDB SQL Reference, Volume 1
and 2
 SC09-4825-00, DB2 UDB Application
Building Guide: Building and Running
Applications V8.1
 SC09-4827-00, DB2 Application
Development Guide: Programming
Server Applications
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References
 DB2 UDB Command Reference, V8.1
 http://www.ibm.com/software/data/db2/d
ata/udb/ad
 ftp://ftp.software.ibm.com/ps/db2/info
 SC26-9944-01 DB2 for Z/OS SQL
Reference
 SC26-9933-01 DB2 for Z/OS
Application Programming and SQL
Guide
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References
• http://www.ibm.com/software/data/db2/os3
90/spb
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References
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F15 Thanks!
Fundamentals of DB2 SQL Procedures
pgunning@breakthroughdb2.com
Anaheim, CA
Sept 9 - 13, 2002
IBM Corporation 2002