Command Codes in IMS DB
What is command code in IMS DB? Its benefits?
Command codes in a SSA makes the call powerful since DL/I treats such SSA’S differently from those without the command codes while performing some special functions.
Command codes save programming and processing time.
Command codes are specified in an SSA following the segment name and an Asterisk ‘*’.
An Asterisk ‘*’ in the ninth position in a SSA indicates that one or more command codes follow the asterisk.
A Blank or Left Parenthesis marks the end of command codes.
ONE or MORE command codes can be used in any combination.
Ten command codes are available under IMS .
F – Locate First Occurrence
L – Locate Last Occurrence
D – Retrieve this segment data into the I-O Area (Path Call)
N – Do not replace this segment
C – Concatenated key in this SSA
Q – Enqueue this segment
U – Maintain current position at this level
V – Maintain current position at this and higher level
P – Establish Parentage at this level
– – Null command code
Proc Option in IMS DB
What is Processing Option? (Proc Option in IMSDB)
Example of PROCOPT
PCB TYPE=DB, DBDNAME=HOSPHIST,
PROCOPT=A, KEYLEN= SENSEG NAME=HOSPITAL,
PARENT=0 SENSEG NAME=WARD,
PARENT=HOSPITAL SENSEG NAME=PATIENT,
PARENT=WARD SENSEG NAME=PBILL,
PARENT=PATIENT PSBGEN LANG=COBOL, PSBNAME=LOGICPSB END
Proc options are the ones whose main function is Data integrity in IMS DB database.
Click here for List of Available Proc Options in IMS DB.
Here are ideas on how to use STOP, START, SHUTDOWN, BOOT mindfully on internal processes of Linux operating systems.
IDCAMS DEFINE Utility you can use to define VSAM files. Here are the parameters to consider while creating them.
Sample SQL Query to Join three tables with WHERE clause. It is Tricky SQL query helpful for interviews.