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1DB2/400 ver 2.0

DB2/400

Version 2.0

Release Date: 25/06/2010

HCL Technologies Ltd.

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Database Management Systems

A system whose overall purpose is to record andmaintain information

A database is a repository for stored data and

programs to manipulate it.

Data Models-

A data modelis a collection of concepts for describing

data

A Schema is a description of a particular collection of

data using the given data model

The relational model is the most widely used model

today

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Levels of Abstraction

Many Viewsand singleConceptual and Physical

Schema

Views Describe how users see

the data Conceptual Schema defines

the logical structure

(Fields)and relation between

them. Physical Schema defines the

physical files and Indexes

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Relational DBMS

Based on Relational Mathematics principles Data is represented in terms of rows and columns of a table

Addresses all types of relations

Easy to design

No anomalies for insert/delete/update

Relational Terminology

Tuple (Row)

Attribute (Column)

Relation (Table)

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Integrity Constraints

A unique key can uniquely identify each row in atable

A primary key is a combination of columns which

uniquely specify a row. It is a special case of

unique keys.

One difference is that primary keys have an

implicit NOT NULL constraint while unique keys

do not.

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The foreign key identifies a column or set of columns in one

(referencing) table that refers to a column or set of columns in another

(referenced) table. The columns in the referencing table must referencethe columns of the primary key or other superkey in the referenced

table.

Integrity Rules -

Entity Integrity-Primary key cannot have null value.

Referential Integrity-Foreign key should be the primary key in the

referenced table.

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Normalization

Normalization - process of removing data

redundancy by decomposing relations in a

Database.

The decomposition approach starts with onerelation and the relation is decomposed intomore number of relations to remove insert,delete and update anomalies.

1NF, 2NF, 3NF and BCNF can be achievedby this approach.

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Un normalized

ClientNo cName propertyNo pAddress rentStart rentFinish rent ownerNo oName

CR76John

kay

PG4

PG16

6 lawrence

St,Glasgow

5 Novar Dr,

Glasgow

1-Jul-00

1-Sep-02

31-Aug-01

1-Sep-02

350

450

CO40

CO93

Tina

Murphy

Tony

Shaw

CR56Aline

Stewart

PG4

PG36

PG16

6 lawrence

St,Glasgow

2 Manor Rd,

Glasgow

5 Novar Dr,

Glasgow

1-Sep-99

10-Oct-00

1-Nov-02

10-Jun-00

1-Dec-01

1-Aug-03

350

370

450

CO40

CO93

CO93

Tina

Murphy

Tony

Shaw

Tony

Shaw

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First Normal Form

First Normal Form is a relation in which the intersection of each There are two approaches to removing repeating groups from

unnormalized tables:

Removes the repeating groups by entering appropriatedata in the empty columns of rows containing the

repeating data.

Removes the repeating group by placing the repeating

data, along with a copy of the original key attribute(s), in aseparate relation. A primary key is identified for the new

relation.

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First Normal Table(1st Approach)

ClientNo propertyNo cName pAddress rentStart rentFinish rent ownerNo oName

CR76 PG4John

Kay

6 lawrence

St,Glasgow1-Jul-00 31-Aug-01 350 CO40

Tina

Murphy

CR76 PG16John

Kay

5 Novar Dr,

Glasgow1-Sep-02 1-Sep-02 450 CO93

Tony

Shaw

CR56 PG4Aline

Stewart

6 lawrence

St,Glasgow1-Sep-99 10-Jun-00 350 CO40

Tina

Murphy

CR56 PG36Aline

Stewart

2 Manor Rd,

Glasgow10-Oct-00 1-Dec-01 370 CO93

Tony

Shaw

CR56 PG16Aline

Stewart

5 Novar Dr,

Glasgow1-Nov-02 1-Aug-03 450 CO93

Tony

Shaw

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1NF with the second approach

ClientNo cName

CR76 John Kay

CR56 Aline Stewart

ClientNo propertyNo pAddress rentStart rentFinish rent ownerNo oName

CR76 PG46 lawrence

St,Glasgow1-Jul-00 31-Aug-01 350 CO40

Tina

Murphy

CR76 PG165 Novar Dr,

Glasgow1-Sep-02 1-Sep-02 450 CO93

Tony

Shaw

CR56 PG46 lawrence

St,Glasgow1-Sep-99 10-Jun-00 350 CO40

Tina

Murphy

CR56 PG362 Manor Rd,

Glasgow10-Oct-00 1-Dec-01 370 CO93

Tony

Shaw

CR56 PG165 Novar Dr,

Glasgow1-Nov-02 1-Aug-03 450 CO93

Tony

Shaw

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Full functional dependency

Full functional dependency indicates that if A and B are

attributes of a relation, B is fully functionally dependent on

A if B is functionally dependent on A, but not on any proper

subset of A.

A functional dependency AB is partially dependent if there

is some attributes that can be removed from A and the

dependency still holds.

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Second Normal Form (2NF)

Second normal form (2NF)is a relation that is in first

normal form and every non-primary-key attribute is fully

functionally dependent on the primary key.

The normalization of 1NF relations to 2NF involves the

removal of partial dependencies. If a partial dependency

exists, we remove the function dependent attributes from

the relation by placing them in a new relation along witha copy of their determinant.

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2NF ClientRental relation

ClientNo cName

CR76 John Kay

CR56 Aline Stewart

Client

ClientNo propertyNo rentStart rentFinish

CR76 PG4 1-Jul-00 31-Aug-01

CR76 PG16 1-Sep-02 1-Sep-02

CR56 PG4 1-Sep-99 10-Jun-00

CR56 PG36 10-Oct-00 1-Dec-01

CR56 PG16 1-Nov-02 1-Aug-03

Rental

propertyNo pAddress rent ownerNo oNamePG4 6 lawrence St,Glasgow 350 CO40 Tina Murphy

PG16 5 Novar Dr, Glasgow 450 CO93 Tony Shaw

PG36 2 Manor Rd, Glasgow 370 CO93 Tony Shaw

PropertyOwner

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Third Normal Form (3NF)

Transitive dependency

A condition where A, B, and C are attributes of a relation such that

if AB and B C, then C is transitively dependent on A via B

(provided that A is not functionally dependent on B or C).Third normal form (3NF)

A relation that is in first and second normal form, and in which

no non-primary-key attribute is transitively dependent on the

primary key.

The normalization of 2NF relations to 3NF involves the removal

of transitive dependencies by placing the attribute(s) in a new

relation along with a copy of the determinant.

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ClientNo cName

CR76 John Kay

CR56 Aline Stewart

Client

ClientNo propertyNo rentStart rentFinish

CR76 PG4 1-Jul-00 31-Aug-01

CR76 PG16 1-Sep-02 1-Sep-02

CR56 PG4 1-Sep-99 10-Jun-00

CR56 PG36 10-Oct-00 1-Dec-01

CR56 PG16 1-Nov-02 1-Aug-03

Rental

propertyNo pAddress rent ownerNo

PG4 6 lawrence St,Glasgow 350 CO40

PG16 5 Novar Dr, Glasgow 450 CO93

PG36 2 Manor Rd, Glasgow 370 CO93

PropertyOwner

3NF ClientRental relation

ownerNo oName

CO40 Tina Murphy

CO93 Tony Shaw

Owner

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System Concepts

Object Oriented Technology :- Everything on AS/400 that can be stored or retrieved is contained in

an Object.

A user is not concerned with the space his object occupies. The

system allocates space automatically.

The Licensed Internal Code that sits above the hardware with an

Object Based Kernel. The Kernel has been written in C++ and is

fully Object Oriented giving all the advantages of flexibility, code

reuse, programming efficiency, and error reduction that come from

Object Oriented Programming.

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Single Level Storage :-

The AS/400 system is a shared system in which all portions ofmain and auxiliary storage are addressed as though they are

within a single area (or level).

The system uses the object name to determine where the object

exists in the system.

operations cannot be performed on an object that is not in main

storage, the system moves a part or all of the object into main

storage as it is needed and moves it back into auxiliary storage

when it is not needed. This transfer is controlled by the system

and does not require control by the user or programmer

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AS/400 Obj t

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AS/400 Objects:

Libraries:A library is an object that is used to group relatedobjects and to find objects by name. Two different objects withthe same can exist in the same library, only if their objects types

differ. However, two objects with the same name and type can

exist in different libraries.

There are three types of libraries :

Systems

User

Product

Folders:A folder is a named object that is used as a directory

for documents and other folders.

Files:File is an object that contains either a set of relatedrecords

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AS/400 Objects:

Programs:A program is an object containing a set ofinstructions that tell the system where to get information, how toprocess it and where to put the results.

Job Queue: The jobq manages the batch request submittedby the users.

Out Queue:As the job processes a request to print data itgets data from a database file and uses the print device file to

format the data.

Message Queue: Communication between programsbetween jobs, between users, between users and programs and

between users and the system occurs through messages.

Data Queue: Programs can set up data queues to be usedby the entire application so that all programs can refer to a

single set of data and variables passed to the programs through

the queue.20

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AS/400 Objects:

User Profiles:A user profile is an object that identifies aparticular user or a group of user to the AS/400 system. Theuser is known in the system by user profile name.

Menu:The menu allows users to select the task they wouldlike to perform without having to use the system commands.

Subsystem:A subsystem is a single, predefined operatingenvironment through which the system coordinates the work

flow and resource use.

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DB2/400

Database Files are files that contain data or provide access to data.

Physical files Type(*FILE) Attribute (PF)

Logical Files Type(*FILE) Attribute(LF)

PF can have only one record format.

Field Reference files are files that contain no data but

contain only descriptions of the fields.

Source Physical files are also database files.

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Physical File

A physical file is composed of four important

parts, Object Header : That contains regular object information

Record Format : Describes the format in which information is

stored.

Access path : Describes the order in which the records are

retrieved.

Data Members - Contains Data

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Physical Files

Data Members

Physical File

Member 1 Member 2 Member 3

The PF s and Source Physical files are the only two files which containdata and are the only files that contain members.

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Physical Files

DDS describes structure the physical file.

File -- blank name type; optional; when used, must precede record type

Record -- R name type; one required for physical file

Field -- blank name type; describes fields; follows record; almostalways present

Key -- K name type; optional; follows field entries

File and field Naming convention

File Name Max of 10 Characters

Record Format Max of 10 Characters Field Names should be unique.

A * in the 7th column of the DDS represents that as a comment

line.

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Field-Level Entries After you insert a record-format line, you can enterfield-level specifications. For these,

you leave the Name Type field blank. But you must enter values for:

Name (field name)

Length (number of characters or digits)

Data Type (e.g., character, zoned decimal, packed decimal, binary, date, time)

For numeric fields, you must also enter the number of decimal positions. Name. For record and field names, use from one to 10 characters, Embedded blanks are

not allowed in a name. Within a record format, field names must be unique.

Length. Length is the number of characters or digits in the field.

For numeric data types, the length specification really means the number ofdigits in the

field.

For date, time, and timestamp types, you do not specify a value for length; it is

determined by type, and for date fields, by format. The values shown (in the previous

slide) for date, time, and timestamp data types are the number of characters needed to

display the stored values, not the number of bytes required for disk storage.

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Field-Level Entries

Data Types

Abbreviation Data type

P Packed decimal

S Zoned decimal

B Binary

F Floating-point (short)

F Floating-point (long)

A Character

H Hexadecimal

L Date

T Time

Z Timestamp

27DB2/400 ver 1.0

For zoned decimal(length 9), then thetrue length of the field is 9 (bytes and

digits). But if the same field is typed P

forpacked decimal, then the value 9

specified for length really means nine

digits, and the true field length is five

bytes. (Length in bytes of a packed-

decimal field can be calculated as (Total

digits / 2) + 1, throwing away any

decimal part.)

This difference in length is due to the

way in which numeric data is stored inpacked-decimal format: two digits per

byte

except for the rightmost

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Field-Level Entries

Advantages of storing numeric data in packed-decimal format: The field itself is smaller (requiring fewer bytes of storage space)

Arithmetic and logic operations are more efficient (requiringfewer intermediate conversion steps)

Minor disadvantages to storing numbers as packed decimal:

A zoned-decimal numeric field of a physical file can be redefinedas a character field through a logical file

NOTE: If you dont explicitly provide a data type, the default is A (alphanumeric/

character) when no decimal-positions value is specified. If you provide a decimal-

positions value and do not specify a data type, DDS defaults to the numeric packed-

decimal (P) data type.

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Field-Level Entries

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If you do not use keyword

DATFMT, the default is

*ISO

format whose display

format isyyyy-mm-dd

(10 characters).

Timestamp data includes

both the date and the time

and is formatted asyyyy-

mm-dd-hh.mm.ss.uuuuuu

(26 characters), whereuuuuuu represents

millionths of a second

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30

Example

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Keywords

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Keywords

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Physical Files

File Level Keywords Unique, LIFO,FIFO,FCFO,REF

Record Level Keywords TEXT

Field Level Keywords CMP,COLHDG,DATFMT,DATSEP,DFT,REFFLD,TEXT,TIM

SEP,VALUES , range

Key Field -Level Keywords DESCEND,ABSVAL

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Physical Files Members

ADDPFM) command adds a named member to a physical file,which must already exist on the system.

The maximum number of members that can be added to the file is

specified for the Maximum members (MAXMBRS) parameter

on the Create Physical File (CRTPF) command or the Change

Physical File (CHGPF) command.

Each member added has the same attributes as those defined in

the physical file, its own set of data records, and its own access

path, as specified in the data description specifications (DDS).

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Physical Files

Common commands On physical Files RUNQRY *N CUSTOMER

DSPPFM CUSTOMER

WITHIN STRSQL - SELECT * FROM CUSTOMER

DLTF CUSTOMER

DSPFFD CUSTOMER DSPFD CUSTOMER

CLRPFM CUSTOMER - Clears the physical File.

CHGPFM

DSPDBR

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Physical Files ConstraintsAdding a Unique Constraint

ADDPFCST FILE(MYLIB/LOCATIONS) TYPE(*UNQCST) KEY(REGION)CST(Personnel_by_REGION)

This command adds a unique constraint to the LOCATIONS file in the MYLIB library.

The field that defines the access path is REGION. The name of the access path is

Personnel_by_REGION.

Adding a Referential Constraint ADDPFCST FILE(ADMN/PERSONNEL) TYPE(*REFCST) KEY(REGION)

CST(1994Hires) PRNFILE(MYLIB/LOCATIONS) PRNKEY(REGION)

DLTRULE(*CASCADE) UPDRULE(*RESTRICT)

This command adds a referential constraint to the PERSONNEL file in the ADMN

library. The field that defines the access path is REGION, which is also the key for the

parent file LOCATIONS in the MYLIB library. The name of the access path is1994Hires. According to the delete rule of cascade, if a record in the LOCATIONS file

is subsequently deleted, and that record matches a record in the PERSONNEL file, the

record also will be deleted from the PERSONNEL file. According to the update rule of

restrict, subsequent changes to the LOCATION file records defined in the constraint are

restricted at the beginning of the update request.

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Adding a Check Constraint

ADDPFCST FILE(PERSONNEL/SALARY) TYPE(*CHKCST)

CST(Upper_Salary_Limit) CHKCST('EMPSAL

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Data dictionary

A Data dictionary is to setup a file with all the data fields used inthe application, but with no data.

whenever the field is needed the DDS for the file points back to

this "dictionary" file (using REF or REFFLD).

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Logical Files

A Logical File is the logical view of a Physical file. Itprovides a access path to the physical File.

Non Join Logical Files

A Non- Join logical file can be either a simple logical file which contains

only one record format or multi record format.

Join Logical Files

Joins 2 - 32 physical files.

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Logical Files

Non Join logical file - Single Record format

Employee State

1000 AP

1001 UP

1002 MP

1003 HA

If file is keyed by state

Employee State

1000 AP

1003 HA1002 MP

1001 UP

Logical Files

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Logical Files

Non Join logical file - Accessing two files - Union on common keyEmployee State Employee Region

1000 AP 1000 HY

1001 UP 1000 VZ

1002 MP 1001 LC

1003 HA 1002 BOIf file is keyed by state

Employee State

1000 AP

1000 HY

1000 VZ

1001 UP

1001 LC

1002 MP

1002 BO

Logical Files

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Logical Files

Join logical file - Joining more than two files.Employee Dept Dept Dept Description

1000 AS AS AS/400

1001 UX UX Unix

1002 LN LN Lexis-Nexis

1003 CS CS Client ServerIf two files are joined by the field.

Employee Dept Description

1000 AS/400

1001 Unix

1002 Lexis-Nexis

1003 Client Server

Natural join, - Only matching from both files

Left outer join - All records from primary missing secondary defaults

Self join - Joining a file to itself.

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Logical File

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Multi format Logical File

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Logical File Member

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Logical File Member

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If the DTAMBRS parameter is specified on

the CRTLF or ADDLFM command as in

the following example:

DTAMBRS((PF1 M1) (PF2 (M1 M2))

(PF1 M1)

(PF2 (*NONE)) (PF3 M3))

Record format LOGRCD2 is associatedwith physical file member M1 in PF1 and

M1 and M2 in file PF2.

Record format LOGRCD3 is associated

with M1 in PF1 and M3 in PF3. No

members in PF2 are associated with

LOGRCD3.If the same physical file name is

specified on more than one PFILE

keyword, each occurrence of the physical

file name is handled as a different physical

file.

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Logical Files

Non Join Logical file File Level Keywords

REFACCPTH, DYNSLT,UNIQUE,FIFO...

Record Level Keywords

PFILE

Field Level Keywords

SST,CONCAT,RENAME

Key Field -Level Keywords

DESCEND,ABSVAL

Select Omit level keywords

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Logical Files

Join Logical file File Level Keywords

JDFTVAL

Record Level Keywords

JFILE,JOIN,JFLD

Field Level Keywords

JREF,

Key Field -Level Keywords

DESCEND,ABSVAL

Select Omit level keywords

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Logical File

Example of a self joinEMPNO EMPNAM MGRNO200 Srinivas 400

400 Sanjay 700

700 S Murali 800

EMPNO EMPNAM MGR Name

200 Srinivas Sanjay

400 Sanjay S Murali

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Join Logical File

50

C

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Commands CPYF

CPYF FROMFILE(PERSONNEL/PAYROLL) TOFILE(TESTPAY/PAYROLL) MB

ROPT(*ADD) CRTFILE(*YES) ERRLVL(10)

Because MBROPT(*ADD) is specified, the copied records are added to any existing records in the

to-file member. Because RCDFMT(*NONE) is assumed, the to-file TESTPAY/PAYROLL must

have the same record format as the from-file. If more than ten recoverable errors occur during the

copy operation, the operation ends.

CPYSRCF

CPYSRCF FROMFILE(QGPL/QCLSRC) TOFILE(MYLIB/CLSRC) FROMMBR(PGMA)

This command copies records from member PGMA of database source file QCLSRC which is in the

QGPL library.

CRTDUPOBJ

CRTDUPOBJ OBJ(FILEA) FROMLIB(LIB1) OBJTYPE(*FILE) TOLIB(LIB2) DATA(*YES)

The file named FILEA in library LIB1 is duplicated and stored in library LIB2. Authorities granted forFILEA are granted to the new FILEA in LIB2. The data records, constraints, and triggers

associated with FILEA in library LIB1 are copied to FILEA in LIB2.

WRKOBJ

DSPOBJD

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Diff

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Difference

CPYF copy file member is to copy file content to an existing file.

If file does not exist then user can create a new file. The structure

will be based on source file.

CRTDUPOBJ create duplicate object, create clone exactly as the

source file with structure and content with its link to program and

logical file and its authority setting as well. no need to recompile

pgm that use this file

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S Fil

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Save Files

A save file can be used with save and restore commands tocontain data that would otherwise be written to tape or diskette.A save file can also be used like a database file to read or write

records that contain save or restore information. A save file can

also be used to send objects to another user on network.

Create a save file

Save Object/ Libraries into the save file

Save onto tape or Ship via FTP

CRTSAVF SAVLIB,SAVOBJ

RSTLIB,RSTOBJ

DSPSAVF

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DB2/400

DFU

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DFU

Is a tool used to perform operations on

data physical files.

Can be used :Enter data,

Update files

File inquiries

STRDFU

T i

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Triggers A trigger defines an event that is to occur with a delete, insert,

update or read (any change) operation on a file.

The trigger program can be specified to be called before or after a

change operation occurs.

A maximum of 300 triggers can be added to one physical file.

Once a trigger is added to the physical file, all members of that

specified file are affected by the trigger.

Trigger program will run for each insert of the record. Say you

copied 100 records. Trigger program will be run for 100 times56DB2/400 ver 1.0

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Uses of triggers

Provide consistent auditing Prevent invalid transactions

Enforce complex business rules

Enforce complex security authorizations

Provide automatic event logging

Automatically generate derived column values Preserving data

consistency across different database tables

Commands-

ADDPFTRG

RMVPFTRG

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WRKQRY

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WRKQRY The Work with Query (WRKQRY) command shows the

Work with Queries display. You can use this display tocreate, display, change, copy, delete, or print a query

definition, or to run a query.

IBM provided query language QUERY/400

This interface is easy to use but is different from PDM.

you can write a query without ever naming it. Of course,you must name it if you wish to save it.

Command-

WRKQRY58

DB2/400 ver 1.0

I t ti SQL

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Interactive SQL

The AS/400 also provides a SQL interface to thenative environment through a interactive SQL

interface.

STRSQL

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Journal ManagementA journal is an AS/400 objects used primarily to record changes to data in a

physical file member and optionally, changes to a logical files access path.

Records file opens, File closes, system IPLs, user generated entries andother types of Activity related to physical file.

When data is changed, a journal always puts after image entries into ajournal receiver. Optionally, you can specify that the journal should put bothbefore image and after images into the journal receiver.

Use Journal Management to recover critical data in AS/400 files.

Journal Management automatically creates a separate copy of file changesand, If necessary, uses the copy to recover data in file.

Commands-

CRTJRNRCV

CRTJRN