OVERVIEW OF SQL PL LANGUAGE ELEMENTS & MODULES

UNIT OBJECTIVES

After completing this unit, you should be able to: Discuss DB2 data types Select the proper data types Work with user-defined data types Work with Row data type Work with Associative arrays Implement data type anchoring Create Module Replace Module Alter Module Drop Module

DB2 BUILT-IN DATA TYPES

USER-DEFINED DISTINCT TYPES

UDTs –User-Defined Data Types: Defined on existing data types

Generates a function to cast between the distinct type and its source type

Generates a function to cast between the source type and its distinct type

Used to enforce business rulesCREATE

ROW DATA TYPE

ARRAY DATA TYPE

Conventional arrayCREATE TYPE arrType AS INTEGER ARRAY[1000];

Associative arrayCREATE TYPE arrType2 AS INTEGER ARRAY[VARCHAR(100)];

CREATE TYPE arrType3 AS myRowType ARRAY[VARCHAR(100)];

ASSOCIATIVE ARRAYS: EXAMPLE (1 OF 2)

ASSOCIATIVE ARRAYS: EXAMPLE (2 OF 2)

DATA TYPE ANCHORING

Keep procedural variables in sync with table columns

Scalar anchoring DECLAREempSalaryANCHORemployee.salary;

Row anchoring DECLARE emp ANCHOR ROWemployee;

BEGINDECLARE emp ANCHOR ROW employee;SETemp.empno= ‘000100’; SETemp.lastname= ‘McClung’;SETemp.firstname= ‘Naomi’;

END

MODULES: OVERVIEW

Module = bundle of several related objects: SPs, UDFs, global variables and cursors, types,

conditions Similar to a class in OO languages (but single

instance)• Four main benefits:

Code organization/structure Scoping

CALL mySchema.myModule.myProc() Information hiding

Each object can be “public” or “private” Global privilege control

Instead of granting/revoking on each SP, UDF or variable

MODULES: MODULE SPECIFICATION

Module that exportsa type, a Stored Procedure, and a User-Defined Function CREATE OR REPLACE MODULE myMod; ALTER MODULE myMod PUBLISH

TYPE myRowTypAS ANCHOR ROW myTab; ALTER MODULE myMod PUBLISH

FUNCTION myFunc(val1 ANCHOR myTab.col1) RETURNS myRowTyp;

ALTER MODULE myMod PUBLISH PROCEDURE myProc(OUTparm1 ANCHOR myTab.col2);

ENDMODULES: MODULE IMPLEMENTATION

MODULES: OTHER STATEMENTS

DROP MODULE myMod; Drops entire module

ALTER MODULE myMod DROP BODY; Drop “implementation”, keeps “specification”

ALTER MODULE myMod DROP PROCEDURE myProc; Drops module object

GRANT EXECUTE ON MODULE myMod TO joe; Grants user joeexecute privilege on all routines

and access to all variables and types in myModModules

UNIT SUMMARY

Having completed this unit, you should be able to: Discuss DB2 data types Select the proper data types Work with user-defined data types Work with Row data type Work with Associative arrays Implement data type anchoring Create Module Replace Module Alter Module Drop Module