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as 400 training institutes in hyderabad
Hi All,
Here we are providing online AS400 Training .
Please contact: messageas400@gmail.com,
Phone no : +91 9505102186
INTRODUCING AS400 AND DB2 400 BASIC PART
As/400
is a special kind of system which was implemented by IBM, Which was
incorporated(merging) with software and hardware.
The
As/400 system was designed especially for developing Bussiness application as
well as run that applications.
As/400
system has it own OS called OS/400 .Database named as DB2/400 and other programming languages
such as rpg3,rpg4,cl/400 etc.
As/400
is Objecct based technology(or) object based system.
OBJECT
An object is a base unit (or)
element and which exists as well as occupies some memory in As/400
server/system on which the Os/400 commands are performed.
àThe examples of objects are….
1)
Library(*lib)
2)
Program(*PGM)
3)
Module(*MODULE)
4)
File(*FILE)
5)
Data
Area(*DTAARA)
6)
DataQ(*DTAQ)
7)
Jobq(*JOBQ)
8)
Outq(*OUTQ)
9)
Userprofile(*USRPRF)
10) Command(*CMD)
11) Jod description(*JOBD)
12) Sub system(*SUBSYSYS)
àEvery object in an As/400 system
has a unique name as well as object type.
àEvery object is identified by its
name and run’s a specific command based on it’s type.
àTo convert RPG3 to RPG4 the
command is CVTRPGLE.
COMMANDS ON LIBRARY:
I.
CRTLIB:
creating library
II.
DLTLIB:deleting
library
III.
WRKLIB:work
with library.
IV.
WRKLIBPDM:work
with library using pdm
V.
EDTLIB:edit
library
VI.
CHGLIBL:change
library list.
VII.
DSPLIBL:display
library list
VIII.
ADDLIBL:add
library list entry.
IX.
RMVLIBLE-removelibrary
list entry.
X.
CHGCURLIB:change
current library.
DB2/400
àDB2/400 is a traditional database use in
an As/400 System .
àDb2/400 is nothing but a
collection of database objects such as source files,physical files,logical
files,triggers,stored proccessors.
àIn an As/400 system there are plenty of files which are all
working with the data.which are as follows…
1)
Database
files.
2)
Display
files
3)
Printer
files
4)
Data
description management files.
5)
Save
files
6)
Interactive communication system files
7)
Message
files.
Database files:
Types of database files.
i.
Source
physical file
ii.
Physical
file
iii.
Logical
file
iv.
Field
reference file
i.
source physical file:
A source physical file is an object of type *file.And
it’s source type /attribute is PF-SRC
Which
is use to store the data which is not
actually the business data which is a source of all other program files etc.
àSource physival file has a
specific record stracture by default when it is created by the command
CRTSRCPF.
àthis record stracture is called
record format of a file which has three fields namely
a)Source
sequence(SRCSEQ):
which
is a length of 6 joined decimal type with no decimal positions.
b)Source
Date(SRCDAT):
which is a length
of 6 joined decimal type with 2 decimal posions.
c)Source
data(SRCDTA):
which is a length
of 80 characters type. the length of the record of Source physical file is 92
which is equal to the sum of all fields in that record format, But the recommended
length is 112 which can be reliable in ILE programs.
The data which is restored in
source physical file record by record in a particular member with a proper
record stricture which follows the record format of source physical file.
When source physical file is
created no member will be associated with it by default, because one of the
parameter of the command CRTSRCPF is member of desired has a value “*none” so
no member will be created in.
Record format:
Record format is nothing but a record
stracture in a file through which all records follow this record
stracture,record format can be defined by a set fields (or) group of fields it
has a control our fields and it also maintains the order of the fields while
retrives the data as well as sending the data from file.
Note:for every file in an as/400
system there is at least on erecord format is defined and the record format has
an unique name in the file.
Member:
Member
is a sub set of data in database fileit is a memory of file where the data is
actually stored,the data records which contain the member follows a specific
record stracture which defined either record format of a file.
In an As/400 system every
database file must contain at least one member it can be a maximum of 32,767
except a source physicalfile which design contain any member at file creation
.if member is not associated with any database file that file is not allowed to
input/output operations.
ii) Physical
file:
physical
file is an object of type *file and it’s source type/attribute is PF-DTA which
is used to stored the actual Bussiness data.
Ø
Physical
file has only one format if does not support for multiple record formats.
Ø
Inorder
to create physicalfile either a command CRTPF or F6 or source member option 14
can be used.
Ø
Inorder
to execute CRTPF no definitions required
.
Ø
To
create PF object with a proper stpes.
THE FOLLOWING
FECILITIES ARE REQUIRED..
v
Data
types
v
Level
entries
v
PDM
tool(program development manager)
v
DDS(data
description specification)
àData types
Ther e are 9 types of
data types in database.
àlevel entries
---file level :entries
:fifo,fcfo,lifo,ref,unique.
---Record format :Text ,Format
---field level : Alias, check, comp/cmp, colhog,
dft, dat sep, ref fld,Text,
Range.Timfmt,timsep,values,allnull
---key field level :Absualute,signed,unsigned,descend.
c)Pdm tool:
In
an AS/400 System thire is a tool set ADTS(application development tools set)
which is IBM supplied tool which hasa lot of tools to define an application
among all tools ADTS,PDm is one of them ,PDM has a lot of features and options
which helps us to make our life easier in developing and working the
application.PDM is started by the start command “STRPDM”
The tool which used/started by pdm
tool as follows.
s.no name Expanssion startcommand
1 DFU datafileutility STRDFU
2 SEU Sourceentryutility STRSEU
3 SQl stracturequarylanguage STRSQL
4 QRY/400 query/400 STRQRY/WRKQRY
5 SDA Screendesignaid STRSDA
6 RLU Report layout
utility STRRLU
7 ISDB interactivesourcedebuger STRISDB
8 FCMU file complier
&merge utility STRFCMU.
CREATING
PF:
Diagrams………………………
àIn order to do the input
/output operatins we have the following
operations.
a.
UPDDTA
b.
DFU
c.
SQL
d.
QRY/400
e.
RPG3/RPG4
f.
CL/400
LOGICAL FILE:
A
LOGICAL FILE is an object of type *file and it’s
source type/attribute LF.
-àLogical file does not contain any data it’s just a
view on physical file
àA logical file can contain a
single record format and more than one record format where as physical file
supports only one.
Advantages of logical file:
A logical file can be
define on a particular physical file to work with the data either in fully or
partially.
àA logical file can be define with
key fields even though the physical file does not have any keyfields.
àA logical file can be define on
obe physical file or morethan one
physical file .
Ø
As/400
is a special kind of system which was implemented by IBM, Which was
incorporated(merging) with software and hardware.
Ø
The
As/400 system was designed especially for developing Bussiness application as
well as run that applications.
Ø
As/400
system has it own OS called OS/400 .Database named as DB2/400 and other programming languages
such as rpg3,rpg4,cl/400 etc.
Ø
As/400
is Objecct based technology(or) object based system.
OBJECT
An object is a base unit (or)
element and which exists as well as occupies some memory in As/400
server/system on which the Os/400 commands are performed.
àThe examples of objects are….
1)
Library(*lib)
2)
Program(*PGM)
3)
Module(*MODULE)
4)
File(*FILE)
5)
Data
Area(*DTAARA)
6)
DataQ(*DTAQ)
7)
Jobq(*JOBQ)
8)
Outq(*OUTQ)
9)
Userprofile(*USRPRF)
10) Command(*CMD)
11) Jod description(*JOBD)
12) Sub system(*SUBSYSYS)
àEvery object in an As/400 system
has a unique name as well as object type.
àEvery object is identified by its
name and run’s a specific command based on it’s type.
àTo convert RPG3 to RPG4 the
command is CVTRPGLE.
COMMANDS ON LIBRARY:
I.
CRTLIB:
creating library
II.
DLTLIB:deleting
library
III.
WRKLIB:work
with library.
IV.
WRKLIBPDM:work
with library using pdm
V.
EDTLIB:edit
library
VI.
CHGLIBL:change
library list.
VII.
DSPLIBL:display
library list
VIII.
ADDLIBL:add
library list entry.
IX.
RMVLIBLE-removelibrary
list entry.
X.
CHGCURLIB:change
current library.
DB2/400
àDB2/400 is a traditional database use in
an As/400 System .
àDb2/400 is nothing but a
collection of database objects such as source files,physical files,logical
files,triggers,stored proccessors.
àIn an As/400 system there are plenty of files which are all
working with the data.which are as follows…
1)
Database
files.
2)
Display
files
3)
Printer
files
4)
Data
description management files.
5)
Save
files
6)
Interactive communication system files
7)
Message
files.
Database files:
Types of database files.
i.
Source
physical file
ii.
Physical
file
iii.
Logical
file
iv.
Field
reference file
i.
source physical file:
A source physical file is an object of type *file.And
it’s source type /attribute is PF-SRC
Which
is use to store the data which is not
actually the business data which is a source of all other program files etc.
àSource physival file has a
specific record stracture by default when it is created by the command
CRTSRCPF.
àthis record stracture is called
record format of a file which has three fields namely
a)Source
sequence(SRCSEQ):
which
is a length of 6 joined decimal type with no decimal positions.
b)Source
Date(SRCDAT):
which is a length
of 6 joined decimal type with 2 decimal posions.
c)Source
data(SRCDTA):
which is a length
of 80 characters type. the length of the record of Source physical file is 92
which is equal to the sum of all fields in that record format, But the recommended
length is 112 which can be reliable in ILE programs.
The data which is restored in
source physical file record by record in a particular member with a proper
record stricture which follows the record format of source physical file.
When source physical file is
created no member will be associated with it by default, because one of the
parameter of the command CRTSRCPF is member of desired has a value “*none” so
no member will be created in.
Record format:
Record format is nothing but a record
stracture in a file through which all records follow this record
stracture,record format can be defined by a set fields (or) group of fields it
has a control our fields and it also maintains the order of the fields while
retrives the data as well as sending the data from file.
Note:for every file in an as/400
system there is at least on erecord format is defined and the record format has
an unique name in the file.
Member:
Member
is a sub set of data in database fileit is a memory of file where the data is
actually stored,the data records which contain the member follows a specific
record stracture which defined either record format of a file.
In an As/400 system every
database file must contain at least one member it can be a maximum of 32,767
except a source physicalfile which design contain any member at file creation
.if member is not associated with any database file that file is not allowed to
input/output operations.
ii) Physical
file:
physical
file is an object of type *file and it’s source type/attribute is PF-DTA which
is used to stored the actual Bussiness data.
Ø
Physical
file has only one format if does not support for multiple record formats.
Ø
Inorder
to create physicalfile either a command CRTPF or F6 or source member option 14
can be used.
Ø
Inorder
to execute CRTPF no definitions required
.
Ø
To
create PF object with a proper stpes.
THE FOLLOWING
FECILITIES ARE REQUIRED..
v
Data
types
v
Level
entries
v
PDM
tool(program development manager)
v
DDS(data
description specification)
àData types
Ther e are 9 types of
data types in database.
àlevel entries
---file level :entries
:fifo,fcfo,lifo,ref,unique.
---Record format :Text ,Format
---field level : Alias, check, comp/cmp, colhog,
dft, dat sep, ref fld,Text,
Range.Timfmt,timsep,values,allnull
---key field level :Absualute,signed,unsigned,descend.
c)Pdm tool:
In
an AS/400 System thire is a tool set ADTS(application development tools set)
which is IBM supplied tool which hasa lot of tools to define an application
among all tools ADTS,PDm is one of them ,PDM has a lot of features and options
which helps us to make our life easier in developing and working the
application.PDM is started by the start command “STRPDM”
The tool which used/started by pdm
tool as follows.
s.no name Expanssion startcommand
1 DFU datafileutility STRDFU
2 SEU Sourceentryutility STRSEU
3 SQl stracturequarylanguage STRSQL
4 QRY/400 query/400 STRQRY/WRKQRY
5 SDA Screendesignaid STRSDA
6 RLU Report layout
utility STRRLU
7 ISDB interactivesourcedebuger STRISDB
8 FCMU file complier
&merge utility STRFCMU.
CREATING
PF:
Diagrams………………………
àIn order to do the input
/output operatins we have the following
operations.
a.
UPDDTA
b.
DFU
c.
SQL
d.
QRY/400
e.
RPG3/RPG4
f.
CL/400
LOGICAL FILE:
A
LOGICAL FILE is an object of type *file and it’s
source type/attribute LF.
-àLogical file does not contain any data it’s just a
view on physical file
àA logical file can contain a
single record format and more than one record format where as physical file
supports only one.
Advantages of logical file:
A logical file can be
define on a particular physical file to work with the data either in fully or
partially.
àA logical file can be define with
key fields even though the physical file does not have any keyfields.
àA logical file can be define on
obe physical file or morethan one
physical file .
Ø
As/400
is a special kind of system which was implemented by IBM, Which was
incorporated(merging) with software and hardware.
Ø
The
As/400 system was designed especially for developing Bussiness application as
well as run that applications.
Ø
As/400
system has it own OS called OS/400 .Database named as DB2/400 and other programming languages
such as rpg3,rpg4,cl/400 etc.
Ø
As/400
is Objecct based technology(or) object based system.
OBJECT
An object is a base unit (or)
element and which exists as well as occupies some memory in As/400
server/system on which the Os/400 commands are performed.
àThe examples of objects are….
1)
Library(*lib)
2)
Program(*PGM)
3)
Module(*MODULE)
4)
File(*FILE)
5)
Data
Area(*DTAARA)
6)
DataQ(*DTAQ)
7)
Jobq(*JOBQ)
8)
Outq(*OUTQ)
9)
Userprofile(*USRPRF)
10) Command(*CMD)
11) Jod description(*JOBD)
12) Sub system(*SUBSYSYS)
àEvery object in an As/400 system
has a unique name as well as object type.
àEvery object is identified by its
name and run’s a specific command based on it’s type.
àTo convert RPG3 to RPG4 the
command is CVTRPGLE.
COMMANDS ON LIBRARY:
I.
CRTLIB:
creating library
II.
DLTLIB:deleting
library
III.
WRKLIB:work
with library.
IV.
WRKLIBPDM:work
with library using pdm
V.
EDTLIB:edit
library
VI.
CHGLIBL:change
library list.
VII.
DSPLIBL:display
library list
VIII.
ADDLIBL:add
library list entry.
IX.
RMVLIBLE-removelibrary
list entry.
X.
CHGCURLIB:change
current library.
DB2/400
àDB2/400 is a traditional database use in
an As/400 System .
àDb2/400 is nothing but a
collection of database objects such as source files,physical files,logical
files,triggers,stored proccessors.
àIn an As/400 system there are plenty of files which are all
working with the data.which are as follows…
1)
Database
files.
2)
Display
files
3)
Printer
files
4)
Data
description management files.
5)
Save
files
6)
Interactive communication system files
7)
Message
files.
Database files:
Types of database files.
i.
Source
physical file
ii.
Physical
file
iii.
Logical
file
iv.
Field
reference file
i.
source physical file:
A source physical file is an object of type *file.And
it’s source type /attribute is PF-SRC
Which
is use to store the data which is not
actually the business data which is a source of all other program files etc.
àSource physival file has a
specific record stracture by default when it is created by the command
CRTSRCPF.
àthis record stracture is called
record format of a file which has three fields namely
a)Source
sequence(SRCSEQ):
which
is a length of 6 joined decimal type with no decimal positions.
b)Source
Date(SRCDAT):
which is a length
of 6 joined decimal type with 2 decimal posions.
c)Source
data(SRCDTA):
which is a length
of 80 characters type. the length of the record of Source physical file is 92
which is equal to the sum of all fields in that record format, But the recommended
length is 112 which can be reliable in ILE programs.
The data which is restored in
source physical file record by record in a particular member with a proper
record stricture which follows the record format of source physical file.
When source physical file is
created no member will be associated with it by default, because one of the
parameter of the command CRTSRCPF is member of desired has a value “*none” so
no member will be created in.
Record format:
Record format is nothing but a record
stracture in a file through which all records follow this record
stracture,record format can be defined by a set fields (or) group of fields it
has a control our fields and it also maintains the order of the fields while
retrives the data as well as sending the data from file.
Note:for every file in an as/400
system there is at least on erecord format is defined and the record format has
an unique name in the file.
Member:
Member
is a sub set of data in database fileit is a memory of file where the data is
actually stored,the data records which contain the member follows a specific
record stracture which defined either record format of a file.
In an As/400 system every
database file must contain at least one member it can be a maximum of 32,767
except a source physicalfile which design contain any member at file creation
.if member is not associated with any database file that file is not allowed to
input/output operations.
ii) Physical
file:
physical
file is an object of type *file and it’s source type/attribute is PF-DTA which
is used to stored the actual Bussiness data.
Ø
Physical
file has only one format if does not support for multiple record formats.
Ø
Inorder
to create physicalfile either a command CRTPF or F6 or source member option 14
can be used.
Ø
Inorder
to execute CRTPF no definitions required
.
Ø
To
create PF object with a proper stpes.
THE FOLLOWING
FECILITIES ARE REQUIRED..
v
Data
types
v
Level
entries
v
PDM
tool(program development manager)
v
DDS(data
description specification)
àData types
Ther e are 9 types of
data types in database.
àlevel entries
---file level :entries
:fifo,fcfo,lifo,ref,unique.
---Record format :Text ,Format
---field level : Alias, check, comp/cmp, colhog,
dft, dat sep, ref fld,Text,
Range.Timfmt,timsep,values,allnull
---key field level :Absualute,signed,unsigned,descend.
c)Pdm tool:
In
an AS/400 System thire is a tool set ADTS(application development tools set)
which is IBM supplied tool which hasa lot of tools to define an application
among all tools ADTS,PDm is one of them ,PDM has a lot of features and options
which helps us to make our life easier in developing and working the
application.PDM is started by the start command “STRPDM”
The tool which used/started by pdm
tool as follows.
s.no name Expanssion startcommand
1 DFU datafileutility STRDFU
2 SEU Sourceentryutility STRSEU
3 SQl stracturequarylanguage STRSQL
4 QRY/400 query/400 STRQRY/WRKQRY
5 SDA Screendesignaid STRSDA
6 RLU Report layout
utility STRRLU
7 ISDB interactivesourcedebuger STRISDB
8 FCMU file complier
&merge utility STRFCMU.
CREATING
PF:
Diagrams………………………
àIn order to do the input
/output operatins we have the following
operations.
a.
UPDDTA
b.
DFU
c.
SQL
d.
QRY/400
e.
RPG3/RPG4
f.
CL/400
LOGICAL FILE:
A
LOGICAL FILE is an object of type *file and it’s
source type/attribute LF.
-àLogical file does not contain any data it’s just a
view on physical file
àA logical file can contain a
single record format and more than one record format where as physical file
supports only one.
Advantages of logical file:
A logical file can be
define on a particular physical file to work with the data either in fully or
partially.
àA logical file can be define with
key fields even though the physical file does not have any keyfields.
àA logical file can be define on
obe physical file or morethan one
physical file .
Ø
As/400
is a special kind of system which was implemented by IBM, Which was
incorporated(merging) with software and hardware.
Ø
The
As/400 system was designed especially for developing Bussiness application as
well as run that applications.
Ø
As/400
system has it own OS called OS/400 .Database named as DB2/400 and other programming languages
such as rpg3,rpg4,cl/400 etc.
Ø
As/400
is Objecct based technology(or) object based system.
OBJECT
An object is a base unit (or)
element and which exists as well as occupies some memory in As/400
server/system on which the Os/400 commands are performed.
àThe examples of objects are….
1)
Library(*lib)
2)
Program(*PGM)
3)
Module(*MODULE)
4)
File(*FILE)
5)
Data
Area(*DTAARA)
6)
DataQ(*DTAQ)
7)
Jobq(*JOBQ)
8)
Outq(*OUTQ)
9)
Userprofile(*USRPRF)
10) Command(*CMD)
11) Jod description(*JOBD)
12) Sub system(*SUBSYSYS)
àEvery object in an As/400 system
has a unique name as well as object type.
àEvery object is identified by its
name and run’s a specific command based on it’s type.
àTo convert RPG3 to RPG4 the
command is CVTRPGLE.
COMMANDS ON LIBRARY:
I.
CRTLIB:
creating library
II.
DLTLIB:deleting
library
III.
WRKLIB:work
with library.
IV.
WRKLIBPDM:work
with library using pdm
V.
EDTLIB:edit
library
VI.
CHGLIBL:change
library list.
VII.
DSPLIBL:display
library list
VIII.
ADDLIBL:add
library list entry.
IX.
RMVLIBLE-removelibrary
list entry.
X.
CHGCURLIB:change
current library.
DB2/400
àDB2/400 is a traditional database use in
an As/400 System .
àDb2/400 is nothing but a
collection of database objects such as source files,physical files,logical
files,triggers,stored proccessors.
àIn an As/400 system there are plenty of files which are all
working with the data.which are as follows…
1)
Database
files.
2)
Display
files
3)
Printer
files
4)
Data
description management files.
5)
Save
files
6)
Interactive communication system files
7)
Message
files.
Database files:
Types of database files.
i.
Source
physical file
ii.
Physical
file
iii.
Logical
file
iv.
Field
reference file
i.
source physical file:
A source physical file is an object of type *file.And
it’s source type /attribute is PF-SRC
Which
is use to store the data which is not
actually the business data which is a source of all other program files etc.
àSource physival file has a
specific record stracture by default when it is created by the command
CRTSRCPF.
àthis record stracture is called
record format of a file which has three fields namely
a)Source
sequence(SRCSEQ):
which
is a length of 6 joined decimal type with no decimal positions.
b)Source
Date(SRCDAT):
which is a length
of 6 joined decimal type with 2 decimal posions.
c)Source
data(SRCDTA):
which is a length
of 80 characters type. the length of the record of Source physical file is 92
which is equal to the sum of all fields in that record format, But the recommended
length is 112 which can be reliable in ILE programs.
The data which is restored in
source physical file record by record in a particular member with a proper
record stricture which follows the record format of source physical file.
When source physical file is
created no member will be associated with it by default, because one of the
parameter of the command CRTSRCPF is member of desired has a value “*none” so
no member will be created in.
Record format:
Record format is nothing but a record
stracture in a file through which all records follow this record
stracture,record format can be defined by a set fields (or) group of fields it
has a control our fields and it also maintains the order of the fields while
retrives the data as well as sending the data from file.
Note:for every file in an as/400
system there is at least on erecord format is defined and the record format has
an unique name in the file.
Member:
Member
is a sub set of data in database fileit is a memory of file where the data is
actually stored,the data records which contain the member follows a specific
record stracture which defined either record format of a file.
In an As/400 system every
database file must contain at least one member it can be a maximum of 32,767
except a source physicalfile which design contain any member at file creation
.if member is not associated with any database file that file is not allowed to
input/output operations.
ii) Physical
file:
physical
file is an object of type *file and it’s source type/attribute is PF-DTA which
is used to stored the actual Bussiness data.
Ø
Physical
file has only one format if does not support for multiple record formats.
Ø
Inorder
to create physicalfile either a command CRTPF or F6 or source member option 14
can be used.
Ø
Inorder
to execute CRTPF no definitions required
.
Ø
To
create PF object with a proper stpes.
THE FOLLOWING
FECILITIES ARE REQUIRED..
v
Data
types
v
Level
entries
v
PDM
tool(program development manager)
v
DDS(data
description specification)
àData types
Ther e are 9 types of
data types in database.
àlevel entries
---file level :entries
:fifo,fcfo,lifo,ref,unique.
---Record format :Text ,Format
---field level : Alias, check, comp/cmp, colhog,
dft, dat sep, ref fld,Text,
Range.Timfmt,timsep,values,allnull
---key field level :Absualute,signed,unsigned,descend.
c)Pdm tool:
In
an AS/400 System thire is a tool set ADTS(application development tools set)
which is IBM supplied tool which hasa lot of tools to define an application
among all tools ADTS,PDm is one of them ,PDM has a lot of features and options
which helps us to make our life easier in developing and working the
application.PDM is started by the start command “STRPDM”
The tool which used/started by pdm
tool as follows.
s.no name Expanssion startcommand
1 DFU datafileutility STRDFU
2 SEU Sourceentryutility STRSEU
3 SQl stracturequarylanguage STRSQL
4 QRY/400 query/400 STRQRY/WRKQRY
5 SDA Screendesignaid STRSDA
6 RLU Report layout
utility STRRLU
7 ISDB interactivesourcedebuger STRISDB
8 FCMU file complier
&merge utility STRFCMU.
CREATING
PF:
Diagrams………………………
àIn order to do the input
/output operatins we have the following
operations.
a.
UPDDTA
b.
DFU
c.
SQL
d.
QRY/400
e.
RPG3/RPG4
f.
CL/400
LOGICAL FILE:
A
LOGICAL FILE is an object of type *file and it’s
source type/attribute LF.
-àLogical file does not contain any data it’s just a
view on physical file
àA logical file can contain a
single record format and more than one record format where as physical file
supports only one.
Advantages of logical file:
A logical file can be
define on a particular physical file to work with the data either in fully or
partially.
àA logical file can be define with
key fields even though the physical file does not have any keyfields.
àA logical file can be define on
obe physical file or morethan one
physical file .
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