The Business Value of DB2 UDB for z/OS

Chapter 4. Business resiliency 105

4.2.6 Accessibility and extensibility

Driving DB2 family compatibility and portability have been key focus areas for the

last several versions of DB2.

Extensibility

What makes DB2 a universal database (UDB)? DB2 is branded UDB when it

incorporates key object relational features, such as stored procedures, triggers,

user-defined functions, user-defines data types, and unstructured data

management. Currently, all DB2s, except for VM/VSE, are branded UDB.

Encoding scheme

Support for ASCII tables was added in Version 5, and Unicode was added in

Version 7. Version 8 completed the integration of multiple encoding schema

support by enabling SQL access to EBCDIC, ASCII, and Unicode in the same

SQL statement. The majority of the DB2 catalog tables has been converted to

Unicode. Such key DB2 processes as program preparation and SQL parsing are

done in Unicode.

New workload support

Type 2 and type 4 Java universal drivers are available for use with DB2 for z/OS,

whether your applications run in a zSeries LPAR or off the platform. When your

Java workloads run on the mainframe, the z/OS Application Connectivity to DB2

for z/OS (FMID HDDA210) provides the drivers for the z/OS platform.

The type 2 driver is best used when running in the same LPAR as DB2, using

DB2’s RRS attach facility. The type 4 driver is best used when in a different LPAR

using DRDA to communicate with DB2. The Java drivers that IBM delivers off the

mainframe are developed by the same team and are the same code base,

providing cross-platform compatibility.

Improvements for Open Database Connectivity (ODBC) and .Net continue. DB2

Version 8 delivers extended support and a new SQL cancel capability. See also

Chapter 6, “Readiness for new workloads” on page 135.

SQL enhancement

DB2 family compatibility and portability make it easier to move applications to

DB2 for z/OS to obtain the business resiliency benefits highlighted in this chapter,

without incurring significant application redesign. Figure 4-5 lists some of the

recent SQL improvements. It shows the top porting requirements from major

independent software vendor (ISV) partners. The top requirements were all

incorporated into Version 8 to assist in building and porting applications on DB2

for z/OS.

106 The Business Value of DB2 UDB for z/OS

Figure 4-5 SQL enrichment and portability

In addition, the new SQL Reference for Cross-Platform Development Version 2

guide has been published. You can download this document from the Web at:

http://www.ibm.com/software/data/db2/zos/v8books.html

This guide can assist you in avoiding the decreasing number of cross-platform

differences, which may cause porting problems.

WebSphere enhancements have been included to make these applications more

efficient. READ ONLY USING UPDATE LOCKS and IS NOT DISTINCT FROM

have been added to provide enhanced read, update, and null checking.

Stored procedures

Internal and external stored procedures are important in the support of network

computing. This encapsulated procedural logic, stored close to or in the

database, allows for efficient data access. DB2 supports external stored

procedures written in the languages that are available on the server. These

include COBOL, PL/I, Assembler, C, C++, REXX, and Java. Internal stored

procedures are written in the standard SQL stored procedures language, and are

common with the SQL stored procedures on DB2 UDB for Linux, UNIX, and

Windows. The DB2 Version 8 enhancement, increasing the SQL statement

length to 2 MB, is particularly helpful for these modules.

The DB2 Development Center assists in the building of Java and SQL stored

procedures in DB2 for z/OS. It also has an integrated debugger for SQL stored

procedures. At run time, Workload Manager supports the adjustment of tasks for

the stored procedure workload.

SQL enrichment

Common Table Expression and

Recursion

Multi-row INSERT and FETCH

GET DIAGNOSTICS

IDENTITY column enhancements

Sequences

Dynamic scrollable cursors

CURRENT PACKAGE PATH

Scalar fullselect

Materialized query tables

Unicode SQL, multiple CCSIDs

XML publishing

SQL access to client-side monitoring

variable

Session variables

Top portability requirements

Long SQL object names

Unicode table and SQL support

Scalar full select

Sequences

Common table expressions and

recursive SQL

Multiple distinct clauses

GROUP BY expression

Literals and predicates longer than

255 bytes

Multi-row INSERT and FETCH

SQL statements greater than 32 KB

Materialized query tables