IBM Insight 2014

SQL PL for DB2 for z/OS Application Developers –Programming Tips for Simplifying ApplicationsSession Number IDZ-4219D

Maryela Weihrauch, Distinguished Engineer IBM Corporation, Silicon Valley Laboratory

Meg Bernal, Senior Software Engineer IBM Corporation, Silicon Valley Laboratory

© 2014 IBM Corporation

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SQL PL Programming Tips

• Quick Overview of SQL PL Procedures• Existing Functionality

• Compound Blocks

• Templates

• Naming Resolution Rules

• Dynamic SQL

• XML Support

• DB2 11 Enhancements• Array Data Type Support

• Global Variables

• Autonomous Transactions

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Introduction to SQL Procedures• What is an SQL Stored Procedure?

• A stored procedure that contains only SQL statements

• May use SQL control statements to write the logic part of the program (e.g. WHILE, IF, GOTO, REPEAT, etc.)

• SQL Procedural Language or SQL PL

• Two types of SQL Stored Procedures

• External SQL Procedures (from V5 on) - Generated C program which runs in a WLM environment

• Native SQL Procedures (from DB2 9 on) - The SQL procedure logic runs in the DBM1 address space

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When to Use Native SQL Procedures

• Go To Option When ….• SQL intensive

• Contains minimal application logic

• Lowest billable cost (for remote) and productivity are the most important priorities i.e. the stored procedure execution itself is zIIP offloadable

• Classic Example is TPC-C:

• An OLTP application for order-entry consisting of entering and delivering orders, recording payments, checking the status of orders, and monitoring the level of stock at the warehouses

• Consider Alternatives When ….• Contains significant amount of application logic

• Many IF/WHILE/CASE/REPEAT statements

• Executes math, string, file manipulation functions

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Benefits of Using Templates

• They engrain good programming practices• You can leverage existing programming standards

• Begin all parameters with their own same naming convention e.g. P_ or IN_ or P_IN_

• Begin all variables with their own same naming convention e.g. V_ or x

• Initialize all variables and output parameters at the beginning of the procedure

• They increase the readability and maintainability of the code• Use comments – lots of comments!• Use indentation consistently

• Label all blocks – compound blocks as well as IF, WHILE, etc

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Compound Statements (aka Compound Blocks)• A compound statement contains a block of the following:

• Optional label

• BEGIN keyword

• Declarations for:• SQL Variables

• SQL Conditions

• Return Codes

• Statements

• Cursors

• Handlers

• SQL statements

• END keyword

• Optional label

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Nested Compound Statements (aka Nested Compound Blocks)

• Nested compound statements help to further define the scope of variables, conditions, handlers, cursors, etc to a subset of statements in a procedure

• Nested compound statements allow compound statements to be used in handlers

CREATE PROCEDURE <procedure name> (<parameter list>)…OuterMostBlock:BEGIN

END OuterMostBlock;

InnermostBlock:BEGINEND InnermostBlock;

InnerBlock1:BEGIN

END InnerBlock1;

InnerBlock2:BEGINEND InnerBlock2;

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Using Templates – Specific Ordering-- native SQL PL procedure templateCREATE PROCEDURE <procedure name> (<parameter list>)VERSION <version id>LANGUAGE SQL<option list>OuterMostBlock:BEGIN------------------------------------------------------------------------------- SQL Variable, SQL Condition, Return Code Declarations ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ Statement Declarations ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ DECLARE CURSOR Statements ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ Handler Declarations ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ SQL Procedure Statements ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ Init all output parameters ---------------------------------------------------------------------------------------

END OuterMostBlock;

May be any number of compound blocks itself

Use DEFAULT values for all SQL Variables

MUST specify items in this

order

IN, INOUT, OUT, OUT Out_Return_Code

Declare SQLCODE and SQLSTATE

variables

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Using Templates – Standardized HandlersCREATE PROCEDURE <procedure name>

(…, OUT Out_SQLCODE INTEGER, OUT Out_DiagString VARCHAR(32000), OUT Out_WarnCount INTEGER,OUT Out_TMS TIMESTAMP)

….OuterMostBlock: BEGIN

….---------------------------------------------------------------------------------- Condition Declarations ----------------------------------------------------------------------------------DECLARE WARN_AND_EXIT CONDITION FOR SQLSTATE '80000';

DECLARE ERR_AND_EXIT CONDITION FOR SQLSTATE '90000';

---------------------------------------------------------------------------------- Handler Declarations ------------------------------------------------------------------------------------ Handler declarations for user-defined conditionsDECLARE EXIT HANDLER FOR WARN_AND_EXIT

BEGINSET Out_SQLCODE = SQLCODE;SET Out_DiagString = ‘Warning hit in STP’;SET Out_TMS = CURRENT TIMESTAMP;

END;

DECLARE EXIT HANDLER FOR ERR_AND_EXITBEGIN

SET Out_SQLCODE = SQLCODE;SET Out_DiagString = ‘Error hit in STP’;SET Out_TMS = CURRENT TIMESTAMP;

END;

…-- Handler declarations for generic conditionsDECLARE EXIT HANDLER FOR SQLEXCEPTIONSQLException_Exit_Handler: BEGIN

--SELECT SQLCODE INTO Out_SQLCODE--FROM SYSIBM.SYSDUMMY1;--SET Out_SQLCODE = SQLCODE;SET Out_SQLCODE = SQLCODE;GET DIAGNOSTICS Out_DiagString = ALL STATEMENT;

END SQLException_Exit_Handler;

DECLARE CONTINUE HANDLER FOR SQLWARNINGSQLWarning_Continue_Handler: BEGINSET Out_WarnCount = Out_WarnCount + 1;

END SQLWarning_Continue_Handler;

DECLARE CONTINUE HANDLER FOR NOT FOUNDNotFound_Continue_Handler: BEGINSET xEOF_Reached = 1;

END NotFound_Continue_Handler; ….

END OuterMostBlock;

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Naming Resolution Rules (Variables, Columns, Etc) • Qualify, qualify, qualify!

� Qualify column names with table names

� Qualify SQL parameters by procedure name

� Qualify SQL variables by label of the compound statement

• If no qualification or ambiguous qualification exists:

� The name is checked to see if it is the name of a column of any existing table or a view that is specified in the SQL routine body at the current server

� If the referenced tables or views do not exist at the current server, the name will be checked first as an SQL variable name in the compound statement and then as an SQL parameter name.

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Confusing Naming Resolution ExampleCREATE PROCEDURE NamingProc (INOUT RESULT INTEGER)…OuterMostBlock:BEGIN

DECLARE AMOUNT INTEGER DEFAULT 100;…InnerBlock1:

BEGINDECLARE AMOUNT INTEGER DEFAULT 0;

IF RESULT < 0 THENUPDATE Product_Table SET AMOUNT = AMOUNT;

ELSESET AMOUNT = 50;

SELECT AMOUNT INTO AMOUNT FROM Product_Table WHERE AMOUNT < RESULT;

END InnerBlock1;

SET RESULT = AMOUNT;END OuterMostBlock;

CREATE TABLE Product_Table (AMOUNT INTEGER, RESULT INTEGER,…);

Can only resolve to RESULT parameter Q: Resolve to

column or variable?

Q: Resolve to variable or parameter?

Q: Resolve to column or variable?

Q: Resolve to column or variable?

Can only resolve to RESULT parameter and

OuterMostBlock AMOUNT variable

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Explicitly Qualified Naming Resolution Example

CREATE PROCEDURE NamingProc (INOUT RESULT INTEGER)…OuterMostBlock:BEGIN

DECLARE AMOUNT INTEGER DEFAULT 100;…InnerBlock1:

BEGINDECLARE AMOUNT INTEGER DEFAULT 0;

IF NamingProc.RESULT < 0 THENUPDATE Product_Table SET Product_Table.AMOUNT = InnerBlock1.AMOUNT;

ELSESET OuterMostBlock.AMOUNT = 50;

SELECT Product_Table.AMOUNT INTO InnerBlock1.AMOUNT FROM Product_Table WHERE OuterMostBlock.AMOUNT < Product_Table.RESULT;

END InnerBlock1;

SET NamingProc.RESULT = OuterMostBlock.AMOUNT;END OuterMostBlock;

CREATE TABLE Product_Table (AMOUNT INTEGER, RESULT INTEGER,…);

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Dynamic SQL – Generic handlingCREATE PROCEDURE DYNAMIC_STMNT (IN IN_SCHEMA CHAR(10),

IN IN_SQL_TXT VARCHAR(32000), … )VERSION Y2014M10D01LANGUAGE SQLDYNAMIC RESULT SETS 1MODIFIES SQL DATA QUALIFIER QUAL1SQL PATH PATH1, PATH2, PATH3ISOLATION LEVEL URVALIDATE BINDDYNAMICRULES RUNDISALLOW DEBUG MODEASUTIME LIMIT 10000MAIN_LOGIC: BEGIN…-- DECLARE CURSOR Statements --DECLARE ADHOC_CSR CURSOR WITH RETURN FOR ADHOC_STMT;…-- SQL Procedure Statements --SET CURRENT SCHEMA = IN_SCHEMA;

PREPARE ADHOC_STMT FROM IN_SQL_TXT;

OPEN ADHOC_CSR;END MAIN_LOGIC;

Objects and privileges must exist at CREATE PROCEDURE time or

CREATE fails

Don’t allow debugging on Production system

CPU threshold for proc execution

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Dynamic SQL – Build SQL based on input parametersCREATE PROCEDURE DYNAMIC_STMNT

(IN IN_ID CHAR(10), IN IN_NAME VARCHAR(20),…OUT OUT_SQLCODE CHAR(5), OUT OUT_DIAGSTRING VARCHAR(32000), OUT OUT_END_TMS TIMESTAMP,OUT OUT_ID_IND CHAR(1), …)

VERSION Y2014M10D01LANGUAGE SQLDYNAMIC RESULT SETS 1…MAIN_LOGIC:

BEGIN-- SQL Variable, SQL Condition, Return Code Declarations –DECLARE V_SELECTSTMT VARCHAR(4000);DECLARE ERR_AND_EXIT CONDITION FOR SQLSTATE '90000';…-- DECLARE CURSOR Statements --DECLARE C_CURSOR1 CURSOR WITH RETURN FOR S_STATEMENT;

…-- Handler Declarations --DECLARE EXIT HANDLER FOR ERR_AND_EXITBEGIN

SET OUT_END_TMS = CURRENT TIMESTAMP;END;

DECLARE EXIT HANDLER FOR SQLEXCEPTIONBEGINSET OUT_SQLCODE = SQLCODE;GET DIAGNOSTICS OUT_DIAGSTRING = ALL STATEMENT;

END SQLException_Exit_Handler;

-- SQL Procedure Statements -- Initialize Output ParmsSET OUT_ID_IND = ‘Y’;

VALIDATE_INPUT: BEGINIF (IN_ID IS NULL ) THEN SET OUT_ID_IND = 'N';SIGNAL ERR_AND_EXIT;

END IF;END VALIDATE_INPUT;

BUILD_SQL_TEXT: BEGINSET V_SELECTSTMT = 'SELECT T1.ID ‘ ||

‘ ,T1.NAME '||' FROM T1‘ || ' WHERE ‘ ||

‘T1.ID = IN_ID‘;

IF (IN_NAME IS NOT NULL ) THENSET V_SELECTSTMT = V_SELECTSTMT ||

' AND T1.NAME ='''|| IN_NAME ||''';END BUILD_SQL_TEXT;

PREPARE S_STATEMENT FROM V_SELECTSTMT ;OPEN C_CURSOR1;SET OUT_END_TMS = CURRENT TIMESTAMP;

END MAIN_LOGIC;

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XML Parameters and Variables

• XML is available as a procedure parameter or as an SQL variable inside a Native SQL Procedure

CREATE PROCEDURE XMLPROC(IN IN_XMLPARM XML, IN VCHPARM VARCHAR(32000))LANGUAGE SQL BEGIN

DECLARE myXMLVar XML;

IF (XMLEXISTS('$x/ITEM[value < 200]' passing by ref IN_XMLPARM as "x")) THENINSERT INTO T1 VALUES(IN_XMLPARM);

END IF;

SET myXMLVar = XMLDOCUMENT(XMLELEMENT(NAME "ORDER",

XMLCONCAT(PARM1, IN_XMLPARM)));

INSERT INTO T1 VALUES(myXMLVar );

END #

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Array Data Type Overview• DB2 for z/OS introduces support for Arrays inside SQL

Routines (UDF or Procedure).

• Prior to DB2 11, users might have utilized the following mechanisms to pass data to/from Routines:

• DECLARED GLOBAL TEMPORARY TABLE,

• Concatenated Strings,

• Long lists of parameters, or …

• The Array Data Type consists of an ordered set of elements having the same data type (length, precision, scale, CCSID as appropriate)

• Two Types of Arrays are Supported:

• Ordinary Arrays

• Have a maximum cardinality (2 Billion)

• The data type of the index value is INTEGER

• Associative Arrays

• Do not have a defined upper bound on the number of elements

• The data type of the index values can be an INTEGER or character string (not a LOB)

• Think of arrays as light-weight workfiles

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Native SQL Procedure Processing with Arrays

z/OSAppl pgm DB2

DBM1DDF

EDM pool

SQL PL native logicSQLSQL

ArraySP

Java pgm…

CALL ArraySP

EDM pool

SQL PL native logicSQL

CALL ArraySP

ArraySPCaller

CALL ArraySPCaller

1a*

1b

2

*T4 Driver Only, CALL stmt Only

*native SQL procedures do not run IN the WLM address space but are still running UNDER the WLM; NSPs take on the caller’s WLM priority

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Populating a table from Arrays

CREATE PROCEDURE NEW_PRODUCT_INFO ( )….LANGUAGE SQLMAIN_LOGIC: BEGIN…------------------------------------------------------------------------------- SQL Variable, SQL Condition, Return Code Declarations ---------------------------------------------------------------------------------------DECLARE MYSKUARRAY CHA10ARRAY; DECLARE MYPRICEARRAY DEC92ARRAY; …--------------------------------------------------------------------------------------- SQL Procedure Statements ----------------------------------------------------------------------------------------- construct an array with new SKU values SET MYSKUARRAY = ARRAY['sku99','sku01','sku20','sku04'];

-- construct a 2nd array with new PRICE values SET MYPRICEARRAY = ARRAY[99.00, 1.99, 20.98, 4.96];

-- populate table with values from arrays INSERT INTO PRODUCT (SKU, PRICE) SELECT * FROM UNNEST(MYSKUARRAY,MYPRICEARRAY) AS T(NEW_SKU,NEW_PRICE) ;

END MAIN_LOGIC;

PRODUCT

1.99sku01

20.98sku20

4.96Sku04

SKU PRICE

sku99 99.00

Result table

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Appending elements to an Array – Solution 1CREATE PROCEDURE NEW_PRODUCT_INFO ( )….LANGUAGE SQLMAIN_LOGIC: BEGIN…--------------------------------------------------------------------------------------- SQL Procedure Statements ----------------------------------------------------------------------------------------- populate 1st array with NAMEsSET MYVCHARRAY1 = (SELECT ARRAY_AGG(NAME) FROM FRIENDS); -- populate 2nd array with TELEsSET MYVCHARRAY2 = (SELECT ARRAY_AGG(TELE) FROM FRIENDS); -- determine number of elements in 1st arraySET IDX = CARDINALITY(MYVCHARRAY1);

-- loop over all elements in 2nd arrayWHILE LCV <= CARDINALITY(MYVCHARRAY2) DO

-- assign elements from 2nd array into 1st array SET MYVCHARRAY1[IDX + LCV] = MYVCHARRAY2[LCV]; SET LCV = LCV + 1;

END WHILE;

-- verify results INSERT INTO RESULT_TB(INFO) SELECT * FROM UNNEST(MYVCHARRAY1) AS T(VALUE);

END MAIN_LOGIC;

Result table

FRIENDS

555-1212Meg

555-1313Sarbinder

NAME TELEChris 555-1111

Chris

Meg

Sarbinder

555-1111

555-1212

555-1313

RESULT_TBINFO

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Appending elements to an Array – Solution 2…MAIN_LOGIC: BEGIN…--------------------------------------------------------------------------------------- SQL Procedure Statements ----------------------------------------------------------------------------------------- populate 1st arraySET MYVCHARRAY1 = (SELECT ARRAY_AGG(NAME) FROM FRIENDS);

-- populate result table INSERT INTO RESULT_TB(INFO) SELECT * FROM UNNEST(MYVCHARRAY1) AS T(VALUE);

INSERT INTO RESULT_TB(INFO) VALUES('**********');

-- populate 2nd arraySET MYVCHARRAY2 = (SELECT ARRAY_AGG(TELE) FROM FRIENDS);

-- 'add 2nd array to 1st array'SET MYVCHARRAY1 = (SELECT ARRAY_AGG(VAL.RESULT)

FROM TABLE (SELECT T.VALUE AS RESULT FROM UNNEST(MYVCHARRAY1) AS T(VALUE) UNION ALL SELECT T.VALUE AS RESULT FROM UNNEST(MYVCHARRAY2) AS T(VALUE)) AS VAL);

-- populate result table INSERT INTO RESULT_TB(INFO) SELECT * FROM UNNEST(MYVCHARRAY1) AS T(VALUE);

END MAIN_LOGIC;

FRIENDS

555-1212Meg

555-1313Sarbinder

NAME TELEChris 555-1111

Chris

Meg

Sarbinder

Chris

Meg

Sarbinder

**********

555-1111

555-1212

555-1313

RESULT_TB

INFO

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Appending elements to an Array – Solution 3CREATE FUNCTION APPEND_ARRAY(ARR1 INTARRAYTYPE, ARR2 INTARRAYTYPE)RETURNS INTARRAYTYPEBEGIN

DECLARE COUNTER INT DEFAULT 1;

IF ARR2 IS NULL OR CARDINALITY(ARR2) = 0 THENRETURN ARR1;

END IF;

SET ARR1 = (SELECT ARRAY_AGG(TX.C1 ORDER BY TX.ID) FROM (SELECT U.C1,U.ID FROM UNNEST(ARR1) WITH ORDINALITY AS U(C1,ID) UNION ALLSELECT V.C1,V.ID + CARDINALITY(ARR1) FROM UNNEST(ARR2) WITH ORDINALITY AS V(C1,ID) ) TX(C1,ID)) ;

END IF; RETURN ARR1;

END#

CREATE PROCEDURE PRCAP()DYNAMIC RESULT SETS 1…

MAIN_LOGIC: BEGIN…DECLARE ARR1,ARR2 INTARRAYTYPE; …DECLARE C1 CURSOR WITH RETURN FORSELECT U.C1 FROM UNNEST(ARR1) AS U(C1);

SET ARR1=(SELECT ARRAY_AGG(INT(SALARY)) FROM EMP);SET ARR2=(SELECT ARRAY_AGG(INT(SALARY)) FROM EMP);

SET ARR1= APPEND_ARRAY(ARR1,ARR2);OPEN C1;

END MAIN_LOGIC;

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Passing sets of values –Comma Delimited Concatenated Strings

CREATE PROCEDURE NONARRAY1IN1OUT (IN IN_ARRAY VARCHAR(1000),OUT OUT_ARRAY VARCHAR(1000))

MAIN_LOGIC: BEGIN…-- declare a cursor that invokes a UDF that parses the comma delimited input stringDECLARE ARRAYINCUR CURSOR FORSELECT I_PRICE FROM ITEM, TABLE(String2Set(IN_ARRAY ,',')) AS T(DAT) WHERE I_ID = T.DATFOR FETCH ONLY;

OPEN ARRAYINCUR ;

WHILE (MAIN_LOGIC.EOD = 0 ) DO-- assign local variable to Nth value in comma delimited input stringFETCH FROM ARRAYINCUR INTO MAIN_LOGIC.PRICE;

IF (MAIN_LOGIC.EOD = 0) THEN-- build comma delimited output stringSET OUT_ARRAY = OUT_ARRAY || RTRIM(CHAR(MAIN_LOGIC.PRICE)) || ',' ;

END IF;END WHILE ;

CLOSE ARRAYINCUR ;END MAIN_LOGIC;

Returns data based on Parsed Input String Values

Treat the Input String Like a Table i.e. 1 string from delimited string

= 1 row

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Passing sets of values – Arrays

CREATE PROCEDURE ARRAY1IN1OUT (IN IN_IDARRAY IDARRAY_TYPE,OUT OUT_PRICEARRAY PRICEARRAY_TYPE)

LANGUAGE SQLMAIN_LOGIC: BEGIN

…-- build output array by selecting values directly from table based on input array valuesSELECT ARRAY_AGG (I_PRICE) INTO OUT_PRICEARRAYFROM (SELECT I_PRICE

FROM ITEM, (SELECT ID FROM UNNEST(IN_IDARRAY) AS ITEMID (ID)) AS ITEMID

WHERE I_ID = ITEMID.ID) AS TB FETCH FIRST 1 ROW ONLY;

END MAIN_LOGIC;

Accepts an Array as InputReturns an Array as Output

Returns data based on Input Array Values

Treat an Array like a Table i.e. 1 element = 1 row

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Invoke Native SQL Proc with Array Parms (Java)import java.sql.Array;…public class ArrayTest{ …private void run () throws SQLException {String[] param = new String [20]; // create string variable for (int i = 0; i < ARRAY_COUNT; i++) { param [i] = ""+i; } // init string variable try {java.sql.Array inParam = con.createArrayOf ("VARCHAR", param); // create Array of VARCHAR elements CallableStatement cs = con.prepareCall("CALL ArraySP(?,?)"); // prepare CALL stmtcs.setArray (1, inParam); // indicate Input parm (Parm1) is an Array cs.registerOutParameter (2, java.sql.Types.ARRAY); // indicate Output parm (Parm2) is an Arraycs.execute (); // call the STPArray outArray = cs.getArray (2); // get Output parm data String[] AOut = (String [])outArray.getArray(); // obtain string representationfor(int i = 0; i < AOut.length; i++) { System.out.println(AOut[i]); } // print resultcs.close (); con.close ();

} …}

…public static void main (String[] args) {

ArrayTestVchAll sc = new ArrayTest(); try { sc.run (); } … } }

-- snippet of create procedure statementCREATE PROCEDURE ArraySP (IN InP1 OrdVchArray ,

OUT OutP1 OrdVchArray )

BEGIN…

END;

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Global Variables• Benefits

• Allows users to share information across SQL statements

• Allows capability to set once, use everywhere

• Provides additional security via DB2 GRANT and REVOKE

• Characteristics

• Similar to special registers

• Their definitions are global and shared across different connections

• Their contents are only shared within the same connection

• Each connection maintains its own instantiation

• Their contents are NOT affected by COMMIT nor ROLLBACK

• Use only the UNICODE encoding scheme

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Using and Referencing a Global Variable

-- create a global variableCREATE VARIABLE Charge_Rate DECIMAL(4,2) DEFAULT 0.00;

-- create a procedure that determines charge rate CREATE PROCEDURE Loan_Charge_Rate (IN ID CHAR(5))LANGUAGE SQLBEGIN

.. SELECT SCORE INTO Cust_Score FROM CUSTOMER WHERE ACCOUNT = ID;IF Cust_Score = ‘Good’ THEN SET Charge_Rate = 1.0;ELSE SET Charge_Rate = 3.0;

END;

-- calling applicationmyApp: PROCEDURE(Buyer, Amount);…

CALL Loan_Charge_Rate(Buyer);UPDATE CUSTOMER SET BALANCE = BALANCE + (Amount * Charge_Rate);

END myAPP;

Referencing the GV

Setting the GV

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Autonomous Transactions

• An Autonomous Transactions is:

• A native SQL procedure that runs in its own unit of work

• May perform SQL, COMMITs, and ROLLBACK it’s own SQL

• No uncommitted changes from it’s caller are seen

• Locks are not shared between the caller and the autonomous procedure

• Upon completion of the autonomous procedure, a COMMIT is driven for the autonomous procedure when SQLCODE >=0

• The caller’s work is untouched

• Useful for event or audit logs

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Error Logging Example

Appl_pgm:…INSERT INTO T1 …IF SQLCODE < 0 THEN

CALL ErrorLog_Proc;ROLLBACK; …

End Appl_pgm;

CREATE PROCEDURE ErrorLog_Proc ()LANGUAGE SQLAUTONOMOUSMain_Logic:

BEGIN…INSERT INTO T2 ……

END Main_Logic;

• T1 modifications are unseen by the Autonomous Transaction ErrorLog_Proc

• After successful execution of the Autonomous Transaction ErrorLog_Proc, T2 changes are committed by not T1changes

New keyword to allow NSP to run it it’s own

unit of work

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Developing SQL PL Routines with Data Studio• Full DB2 V11 support

• SQL PL Routines Development

� Stores commonly used patterns as reusable templates

� Validates SQL PL statements in the editor

� Deploys stored procedure to multiple servers

� Steps through routines and inspects variables with graphical debugger

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Tuning and Testing with Data Studio• SQL Tuning

� Displays Access Plan visually

� Runs Statistics Advisor on single query

• Regression Testing

� Compares routines output with base line

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Data Studio – Generic Templates

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Data Studio – Editing Generic Template

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Debugging a Routine

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What about Functions?• Functions may also be written in SQL PL

• May contain logic using SQL PL control statements

• SQL functions are non-inline i.e. package is created

• Parser determines type of function

• Example – Reverse a stringCREATE FUNCTION REVERSE(INSTR VARCHAR(20)) RETURNS VARCHAR(20) DETERMINISTIC NO EXTERNAL ACTION CONTAINS SQL BEGIN

DECLARE REVSTR, RESTSTR VARCHAR(20) DEFAULT ''; DECLARE LEN INT; IF INSTR IS NULL THEN

RETURN NULL; END IF; SET (RESTSTR, LEN) = (INSTR, LENGTH(INSTR)); WHILE LEN > 0 DO

SET (REVSTR, RESTSTR, LEN) = (SUBSTR(RESTSTR, 1, 1) CONCAT REVSTR, SUBSTR(RESTSTR, 2, LEN - 1), LEN - 1);

END WHILE; RETURN REVSTR; END

compiled SQLscalar functions

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Summary

• Standardize coding practices by creating universal templates

• Create a generic procedure to execute dynamic SQL

• Provide greater flexibility of data exchange with global variables

• Consider native SQL PL procedures for new workloads as the array data type and autonomous transactions provide even greater usability

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Websites

• Requirements� https://www.ibm.com/developerworks/rfe/

• DB2 for z/OS Knowledge Center � http://www-

01.ibm.com/support/knowledgecenter/SSEPEK/db2z_prodhome.html

• DB2 11 for z/OS Technical Overview Redbook� http://publibb.boulder.ibm.com/abstracts/sg248180.html?Open

• DB2 9 for z/OS Stored Procedures: Through the CALL and Beyond Redbook� http://www.redbooks.ibm.com/abstracts/sg247604.html?Open

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Maryela WeihrauchIBM Corporation, Silicon Valley Laboratoryweihrau@us.ibm.com

Meg BernalIBM Corporation, Silicon Valley Laboratorymeg@us.ibm.com

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Thank You