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PGLIB=/opt/PostgreSQL/9.1/lib/
LD_LIBRARY_PATH=/opt/PostgreSQL/9.1/lib/
export PGDATA=/opt/PostgreSQL/9.1/data/
export PGDATA PGLIB LD_LIBRARY_PATH


Is it possible to rename a column name?

Posted by jyothsnav 2032 days ago (Editorial)

Yes it is possible to rename a column name in DB2 V9.7 version online.


Exception: If the column to be renamed is a part of primary key, we should drop the primary key, rename the column and then recreate the primary key


Command:


ALTER TABLE <TABNAME> RENAME COLUMN <OLDNAME> TO <NEWNAME>


 


How to find the last used date of an index

Posted by jyothsnav 2032 days ago (Editorial)

In earlier versions of DB2, we donot have the facility to find the last used date of an index. But in V9.7, this feature is available which will help us in analysing the real usage of that index and whether it is required.


Command:


SELECT LASTUSED FROM SYSCAT.INDEXES WHERE INDNAME='?'


OR


SELECT INDNAME,LASTUSED FROM SYSCAT.INDEXES WHERE TABNAME='?'


 

Four Phases of Load Operation

Posted by jyothsnav 2276 days ago (Editorial)

Four Phases of Load operation:


LOAD Phase - four things happen during the load phase; data is read from the source file specified and loaded into the appropriate target table, index key values and table statistics are collected, point of consistency information is recorded and invalid data is placed into dump files.


(LOAD QUERY command is used to monitor the progress/status of

Difference between Import and Load utility

Posted by jyothsnav 2277 days ago (Editorial)

The import utility copies data using SQL insert or update operations, as a result each row processed must be checked for constraint compliance and all activities performed is recorded in the databases transaction log files.


Load utility, inserts data into a table by building data pages consisting of several individual rows of data and writing those pages directly to the table space con

Entity Relationship Diagrams

Posted by jyothsnav 2287 days ago (Editorial)

There are serveral notations for data modeling. The actual model is frequently called Entity Relationship model, because it depicts data in terms of the entities and relationships described in the data. An entity -relationship model (ERM) is an abstract conceptual representation of structured data. Entity-relationship modeling is a relational schema database modeling method, used in software e


Data Modeling

Posted by jyothsnav 2287 days ago (Editorial)

Data modeling is the process of creating a data model by applying formal data model descriptions using data modeling techniques.


Data modeling is a method used to define and analyze data requirements needed to support the business process of an organization. The data requirements are recorded as a conceptual data model with associated data definitions.


Actual i

Conceptual, logical and physical schemas

Posted by jyothsnav 2287 days ago (Editorial)

A data model instance may be one of 3 kinds:


Conceptual Schema: describes the semantics of a domain, being the scope of the model. For example, it may be a model of the interest area of an organization or industry. This consists of entity classes, representing kinds of things of significance in the domain, and relationships assertions about associations between pai

DB2 Load Utility

Posted by jyothsnav 2276 days ago (Editorial)

Like the Import utility, the LAOD utility is designed to read data directly from an external file and store it in a specific table. However, unlike when the import utility is used, when the Load utility is used the table to which data is to be copied must already exist in the database before the load operation is initiated.


Syntax:


LOAD FROM [filename] OF [DEL|ASC|IXF]



DB2MOVE utility

Posted by jyothsnav 2277 days ago (Editorial)

Its easy to see how the export utility can be used together with the import utility or load utility to copy a table from one database to another, but what if we want to copy several tables or an entire database?


In this case, data can be copied table by table using export/import/load but a more efficient way to copy an entire DB2 database is by using the DB2MOVE utility.


DB2MOV

DB2 Import Utility

Posted by jyothsnav 2277 days ago (Editorial)

One way to copy data from an external file to a database is by using DB2's import utility; the import utility is desgined to read data directly from an external file (provided the file is written in a format that is supported by DB2) and insert it in a specific table or updatable view.


Syntax:


IMPORT FROM [filename] OF [DEL|ASC|IXF|WSF]


COMMITCOUNT [commitcount] | COMMI

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