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What is the difference between IN subselects and EXISTS subselect?
If there is an index on the attributes tested an IN is more efficient since DB2 uses the index for the IN. (IN for index is the mnemonic).
nlarsensmith
- Feb 22nd, 2011
***IN***IN subselects perform search on a list of values returned by the subquery.ex)select * from table1 where col1 IN(select col1 from table2 where <some condition>)-Based on the range of...
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Can an index of a table be displayed using 'DISPLAY' ?
BrantleyL1
- Jul 27th, 2011
However, here is an easy solution:
code in ws...
01 ws-index pic S9(8) comp.
set ws-index to (table-index)
display ws-index. -
DB2 Large Objects (LOB) Columns
In DB2, Large Objects (LOB) Columns are used to store large objects (Documents, pictures, voice, and mixed media) in database. Which of the following clauses can't be used on LOB columns?a) GROUP BYb) HAVINGc) ORDER BYd) NONE OF THE ABOVE
kris mohan
- Sep 13th, 2011
None of the above
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What is a DB2 plan?
An application plan or package is generated by the bind to define an access path.
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What is the full form of DBRM ?
a.Database Restrict Modelb.Database Resurrect Modelc.Database Request Moduled.Database Reference Modulee.Database Restrict ModuleDatabase Request Module
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Given a read-only application that requires consistent data for every query, which isolation levels should it use to provide the most concurrency with other applications doing updates?
Given a read-only application that requires consistent data for every query, which of the following isolation levels should it use to provide the most concurrency with other applications doing updates? A. Read Stability B. Repeatable Read C. Cursor Stability D. Uncommitted Read
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How the durability(one amongst the ACID model) of database is achieved while loading table with 'Log No' option?
manasa
- Nov 4th, 2011
When we load data with LOG NO then the table goes to copy pending status and is not available for updating..
It can be accessed for read only.
So,we need to take a image copy which will change the copy pending status to RW.
This IC will be used as a backup and thus durability can be achieved. -
I have 1000 records in vsam,I want to read records 500 to 900?
prasenjit_in
- Sep 2nd, 2008
last 2 who answered the query didnt you see that its a VSAM based question...dont just put up anything and everything.
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-811 abend
When will occur -811 abend? how will u resolve the -811 abend?
rasheeed17
- Jan 19th, 2012
- You will get -811 abend when your SQL query returns more than one record. - COBOL do not have ability to handle more than one db2 record at a time. - You must USE CURSOR If your query returns mor...
6983manish
- Nov 12th, 2011
If the need is to get any of the row qualified for the predicates given , you can use "Fetch First 1 Row Only" with your select query.
OR
If you are interested all the data qualified for the query , there is no option except the use of Cursors. -
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How can you split db2 table in to exactly half?
Can we divide it row wise or col wise.?is there any query for this.?
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What is an asynchronous write?
. It is a write to disk that may occur before or long after a commit. The write is controlled by the buffer manager.
krsna
- Jun 7th, 2012
Asynchronous write is when the pages from bufferpool is written to disk by the page cleaners.
Sandhya.Kishan
- Apr 6th, 2012
Asynchronous write is a function where the the function call immediately returns after the operation was enqueued or if before this happens an error was encountered.This function is present in "aio.h"...
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What is a root page?
The opposite of a leaf page; it is the highest level index page. An index can contain only the one root page; all other index pages are associated to the root.
Sandhya.Kishan
- Jul 9th, 2012
The indexes of DB2 are represented using b-tree,the b-trees top page is called as the root page.The root page entries represent the upper range limits of the index and are referenced first in a search.
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How does Db2 use multiple table indexes?
DB2 use the multiple indexes to satisfy multiple predicates in a SELECT statement that are joined by an AND or OR.
Sandhya.Kishan
- Jul 9th, 2012
By using the concept of list prefetch DB2 uses multiple index processing.I is used to satisfy multiple predicates in a select statement that are joined by an AND or OR.
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What is the self-referencing constraint?
A31. The self-referencing constraint limits in a single table the changes to a primary key that the related foreign key defines. The foreign key in a self referencing table must specify the DELETE CASCADE rule.
Sandhya.Kishan
- Jul 9th, 2012
Self-referencing constraint makes the table both the parent and dependent table in the same referential constraint.
Here the table is created first and then the foreign key is defined to that table. -
What is lock contention?
To maintain the integrity of DB2 objects the DBD permits access to only on object at a time. Lock contention happens if several objects are required by contending application processes simultaneously.
Sandhya.Kishan
- Jul 9th, 2012
Lock contention are used for maintaining concurrency in the DB2? environment.There are several types of contention situations that degrade DB2 performance, including suspension, timeout, and deadlock.
Begin program-specific programming interface information.
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Bind Parameters
What are the important bind parameters to be used in bind card? What is the significance of each parameter?
Mandar Dindorkar
- Jul 27th, 2012
I will say the Answer Depends barring a few parameters which are mostly used. 1) ISOLATION -> Isolation Level to decide level of locking used along with LOCK parameters on the DB2 objects. 2) ACQUI...
jzmoonrock56
- Aug 31st, 2011
The bind parameters are generally generic the most important is isolation level which is always CS and sometimes UR if you want to rock right thru.
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What is check pending and copy pending status in DB2, how do you resolve it?
Mandar Dindorkar
- Jul 27th, 2012
Check Pending is when you have data added to the table using either insert or LOAD utility which violate table check constraints. The IBM DB2 LOAD UTILITY has ENFORCE CONSTRAINTS and similar options w...
Mohit
- May 28th, 2012
SET INTEGRITY Option....please read IBM libraries before using this.
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What is a DB2 access path?
An access path is the method used to access data specified in DB2 sql statements.
Mandar Dindorkar
- Jul 27th, 2012
DB2 Access path is (in most cases) the path which results in the most optimized execution of an SQL query. Whenever any Static SQL (Embedded SQL) is bound to a package/plan, the DB2 optimizer creates...
jzmoonrock56
- Aug 31st, 2011
The access path is determined by DB2 during the bind process. This determines what indexes will be used.
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Difference between Embedded SQL and Dynamic SQL?
Mandar Dindorkar
- Jul 27th, 2012
Embedded SQL -> Access Path is generated during BIND time. also table authorizations are checked during BIND (if VALIDATE(BIND) is used).
Dynamic SQL => Access path is generated during Run-time. Table authorizations can only be checked during run-time.kalone
- Feb 1st, 2010
STATIC sql(embedded) : It is hardcoded in the program itself and the changeable &n...
DB2 Interview Questions
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