as400 interview questions and answers-Part 28
1. Explain SETLL opcode with example.
Ans:
SETLL (E) (Set
Lower Limit)
·
SETLL sets the file pointer at the first
occurrence of the record where the key field/RRN value is greater than or equal
to the factor-1 search argument value.
·
After positioning the file pointer we can go for
any file operation e.g. READ, READP,READPE, READE.
- If the SETLL operation is not
successful (no records found condition), the file is positioned to the end
of the file.
·
In factor-1 we can use figurative constant
*LOVAL, *HIVAL, *START, *END or we can use RRN VALUE or KEY VALUE or KEY LIST.
·
We use %FOUND to determine if the record found
is having the key field/RRN value greater than or equal to the key field. In
this case HI indicator will be *on.
·
We use %EQUAL to determine if the record found
is having the key field/RRN value exactly same as the search argument value in
factor-1.
·
For sequential file we can use RRN value only.
In this case EQ indicator will be *on.
·
To handle SETLL exceptions (file status codes greater
than 1000), either the operation code extender 'E' or an error indicator at LO
level can be used.
·
The Equal Indicator gets turned-on if and exact
match is found. We can use this in place of %equal().
·
If Greater value match is found then HI level
indicator will get turned on. We can use this in place of %found().
·
*LOVAL doesn’t work for non-keyed file.
·
SETLL if successful sets EOF() *OFF if it is
*ON, else if not successful doesn’t do anything to EOF().
·
For a descending order file, to read the first
record we can do:
*HIVAL
SETLL File001
READ
·
For a descending order file, to read the last
record we can do:
*LOVAL
SETLL File001
READP
·
For an ascending order file, to read the first
record we can do:
*LOVAL
SETLL File001
READ
·
For an ascending order file, to read the last
record we can do:
*HIVAL
SETLL File001
READP
·
If a new record is added or a key field altered
after a SETLL operation with either *LOVAL or *HIVAL, the file may no longer be
positioned to the record with the lowest or highest key.
·
The SETLL operation does not apply the lock on
the file hence if we just want to check the existence of a record it is better
to go for SETLL instead of using CHAIN which locks the records and copies the
data into input buffer leading to performance issue.
|
Factor 1
|
Op-code
|
Factor 2
|
Result Field
|
Resulting Indicators
HI LO EQ
|
|
Search
argument
|
SETLL(E)
|
File
or record format name
|
|
Greater
value match found
|
Error
|
Exact
match found
|
Example-I : SETLL for sequential
file
000001 setll filename (instead
of: *LOVAL SETLL REC1)
Example-II
: SETLL does not set EOF to *ON if not successful.
Physical
file used in the program = PF0001
PNAME PNUM PADDR OPNDD OPNMM OPNYY OPNSTS
AMINEM P00000000001 CONIZA TOJ 2 1 2,012 1
IROBO P00000000002 HENGURIZZA 1 6 2,012 1
ZENNIE P00000000003 UENAI 13 1 2,012 2
JOHNNE P00000000004 HOLLYNIA 14 2 2,011 1
JENNUMA P00000000008 UNIBAR 9 1 2,011 2
******** End of report ********
·
First of all
put ‘P00000000001’ in factor-1 for SETLL operation.
Columns . . . : 6 80 Browse AMITCC/QRPGLESRC
SEU==> OP_SETLL
FMT FX FFilename++IPEASF.....L.....A.Device+.Keywords+++++++++++++++++++++++++++++
*************** Beginning of data ****************************************************
0001.00 FPF0001 IF E K DISK 130211
0003.00 C 'P00000000001'SETLL REC2 130212
0004.00 C IF %EQUAL(PF0001) 130211
0005.00 C 'EXACT MATCH' DSPLY 130211
0006.00 C ELSEIF %FOUND(PF0001) 130211
0007.00 C 'HIGHER MATCH'DSPLY 130211
0008.00 C ELSEIF %EOF(PF0001) 130212
0009.00 C 'END OF FILE' DSPLY 130212
0010.00 C ELSE 130211
0011.00 C 'NO RECORDS' DSPLY 130212
0012.00 C ENDIF 130211
0013.00 C SETON LR 130128
****************** End of data *******************************************************
OUTPUT
·
Now we put ‘P00000000007’
in factor-1 for SETLL operation.
Columns . . . : 6 80 Browse AMITCC/QRPGLESRC
SEU==> OP_SETLL
FMT FX FFilename++IPEASF.....L.....A.Device+.Keywords+++++++++++++++++++++++++++++
*************** Beginning of data ****************************************************
0001.00 FPF0001 IF E K DISK 130211
0003.00 C 'P00000000007'SETLL REC2 130212
0004.00 C IF %EQUAL(PF0001) 130211
0005.00 C 'EXACT MATCH' DSPLY 130211
0006.00 C ELSEIF %FOUND(PF0001) 130211
0007.00 C 'HIGHER MATCH'DSPLY 130211
0008.00 C ELSEIF %EOF(PF0001) 130212
0009.00 C 'END OF FILE' DSPLY 130212
0010.00 C ELSE 130211
0011.00 C 'NO RECORDS' DSPLY 130212
0012.00 C ENDIF 130211
0013.00 C SETON LR 130128
****************** End of data *******************************************************
OUTPUT
·
Now we put ‘P00000000009’
in factor-1 for SETLL operation.
Columns . . . : 6 80 Browse AMITCC/QRPGLESRC
SEU==> OP_SETLL
FMT FX FFilename++IPEASF.....L.....A.Device+.Keywords+++++++++++++++++++++++++++++
*************** Beginning of data ****************************************************
0001.00 FPF0001 IF E K DISK 130211
0003.00 C 'P00000000009'SETLL REC2 130212
0004.00 C IF %EQUAL(PF0001) 130211
0005.00 C 'EXACT MATCH' DSPLY 130211
0006.00 C ELSEIF %FOUND(PF0001) 130211
0007.00 C 'HIGHER MATCH'DSPLY 130211
0008.00 C ELSEIF %EOF(PF0001) 130212
0009.00 C 'END OF FILE' DSPLY >>>>>>> SETLL never sets EOF if it doesn’t 130212
0010.00 C ELSE find a record 130211
0011.00 C 'NO RECORDS' DSPLY 130212
0012.00 C ENDIF 130211
0013.00 C SETON LR 130128
****************** End of data *******************************************************
OUTPUT
Example-II
: SETLL sets EOF to *OFF, if successful
Columns . . . : 6 80 Browse AMITCC/QRPGLESRC
SEU==> OP_SETLL2
FMT FX FFilename++IPEASF.....L.....A.Device+.Keywords+++++++++++++++++++++++++++++
*************** Beginning of data ****************************************************
0001.00 FPF0001 IF E K DISK 130211
0003.00 C *HIVAL SETLL PF0001 130212
0004.00 C READ PF0001 130212
0005.00 C IF %EOF(PF0001) 130212
0006.00 C 'END OF FILE' DSPLY 130212
0007.00 C ENDIF 130212
0008.00 C 'P00000000001'SETLL REC2 130212
0009.00 C IF %EQUAL(PF0001) 130212
0010.00 C 'EXACT MATCH' DSPLY 130211
0011.00 C ELSEIF %FOUND(PF0001) 130211
0012.00 C 'HIGHER MATCH'DSPLY 130211
0013.00 C ELSE 130211
0014.00 C 'NO RECORDS' DSPLY 130212
0015.00 C ENDIF 130211
0016.00 C IF NOT %EOF(PF0001) 130212
0017.00 C 'NOT EOF' DSPLY 130212
0018.00 C ENDIF 130212
0019.00 C SETON LR 130128
****************** End of data *******************************************************
OUTPUT
END OF FILE
EXACT MATCH
NOT EOF