IBM DB2 Interview Preparation Guide

Bind parameters are:
MEMBER - In bind package,
LIRARY - DBRM library name ,
ACTION(add/replace)- package or plan can be add or replace.
ISOLATION - Determines the duration of the page lock.
AQUIRE - Lock a tableon use
RELEASE - releases when the plan terminates
VALIDATE - It will be check about authorization.
EXPLAIN - loads the access path selected by the optimizer
in table

Updating a column: You can update columns in the rows that
you retrieve. Updating a row after you use a cursor to
retrieve it is called a positioned update. If you intend to
perform any positioned updates on the identified table,
include the FOR UPDATE clause. The FOR UPDATE clause has
two forms:
• The first form is FOR UPDATE OF column-list. Use
this form when you know in advance which columns you need
to update.
• The second form is FOR UPDATE, with no column list.
Use this form when you might use the cursor to update any
of the columns of the table.
For example, you can use this cursor to update only the
SALARY column of the employee table:

EXEC SQL
DECLARE C1 CURSOR FOR
SELECT EMPNO, FIRSTNME, MIDINIT, LASTNAME, SALARY
FROM DSN8810.EMP X
WHERE EXISTS
(SELECT *
FROM DSN8810.PROJ Y
WHERE X.EMPNO=Y.RESPEMP
AND Y.PROJNO=:GOODPROJ)
FOR UPDATE OF SALARY;

If you might use the cursor to update any column of the
employee table, define the cursor like this:

EXEC SQL
DECLARE C1 CURSOR FOR
SELECT EMPNO, FIRSTNME, MIDINIT, LASTNAME, SALARY
FROM DSN8810.EMP X
WHERE EXISTS
(SELECT *
FROM DSN8810.PROJ Y
WHERE X.EMPNO=Y.RESPEMP
AND Y.PROJNO=:GOODPROJ)
FOR UPDATE;

DB2 must do more processing when you use the FOR UPDATE
clause without a column list than when you use the FOR
UPDATE clause with a column list.

There is no difference. But it is always better to declare
Cursor in Working-Storage Section because you will not code
Open Cursor before Declare Cursor by mistake. It is just a
standard to declare Cursor in WSS. As best practice to
avoid oversight.

when u bind , 5 queries has 5 sql statements in 1 DBRM, its
regroup into 1 package, 1 plan...Plan is a collection of
packages..
correct me if i'm wrong..

You should pass CHECKpoint frequency value from JCL to
cobol program.Intern cobol program will have the table of
retart logic.
Table contents(coloumns)be: 1.No of records ,2.No of
records + 1, 3.no of records processed etc.
Once the updattion or insertion got stucked while
processing ,All the relative data will be stored the above
mentioned table.

So check the record from table .Fix the abend and restart
your job for the failed step.

This is mainly production support work .manually u have to
check the record .and get the records info from the table
and restart the job from the failed step

Arrays are not supported by sql so trying to add an array in
a where clause of sql may throw some errors...
only dot operators are possibly used.

Thru SPUFI/QMF/FileAID you can insert bulk records by
selecting the records from one table and inserting into
other one.

select * from sysibm.syscolumns where name = <name you 3
columns here>

The above query to metadata will show you the list of table
names where these 3 columsn present

when we are tying to update a table having 100 rows.
if the program abends when updating 51 row . how to start
updating again from the 51 row .
what was the logic


Ans: The Possible answer would be..if you had used COMMIT
before 51st ROW .. the Former records
would have been updated in the table .. If No COMMIt was
used.. The whole transaction would have been
ROLLBACKED.

Now If you want to start a fresh Transaction and want to
start Updating directly from 51st Row
Then There are two ways

1> Perform a loop to scroll till u have read 50 rows
Then Point ur cursor as CURRENT to the 51st Row
Start Updating the Records Till end of table.

or

2> Declare a Scrollable cursor & use FETCH ABSOLUTE option
to fetch a particular row directly


EXEC SQL FETCH ABSOLUTE +51 C1
INTO :TEMP1, :TEMP2, :TEMP3;

using select in embedded sql with where clause should fetch
only one row , but cursor can be used when we need more rows
to be retrieved one at a time.

In case more than one row is retrieved in a select clause it
will throw -811 sql error.