Important questions to be remembered by a Oracle Consultant Part3

Important questions to be remembered by a Oracle Consultant,
Difference between Conversions and Interfaces?
Conversion is to bring the data from other (non-Ora Apps) system to Oracle-Application system. This is one time activity (bring account details, transactions, orders, receipts and so on. So conversion itself is a project.

Interfaces are Concurrent Programs/Program sets (pl/sql, pro*C, unix scripts, executables) . Interfaces are basically of two types (Oracle supplied (vanila programs eg: Auto invoice in AR) and created by developer).
Hope this clarifies the concepts.
Conversion means one time activity interface means periodic activity.
example:- to transfer the data old version to new version it is called conversion to transfer the data from staging table to interface table it is called interface , it is process on every day or every hour ........

Which module is not a multi org?
General Ledger and CRM Foundation Modules

What are the types of Concurrent Managers?Can we delete a Concurrent Manager?
There are many concurrent managers, each monitoring the flow within each apps area.
1. Internal Concurent Manager (ICM): This is the one which monitors all other CMs
2. Standard Manager (SM) : This takes care of report running and batch jobs
3. Conflict Resolution Manager (CRM): checks concurrent program definitions for incompatability checks.
We cannot delete a concurrent manager... but we can disable it... but it's not recommended.

Trading community Architecture(TCA)
ICA (Internet Computing Architecture)

What are AP setup steps ?
setup---->suppliers....>invoices..>payments.....>reports......>periods.....>transfer to GL

What does US mean in appl_top/au/11.5.0/reports/US?
US is the language directory specifying that the source files to be placed under this dir is for English/American Language.

This is the standard of apps directory structure that for very language you implement oracle apps there should be a language specific folder

What are SQL CODE and SQL ERRM and why are they important for PL/SQL developers? 
SQL CODE returns the value of the error number for the last error encountered. The SQLERRM returns the actual error message for the last error encountered. They can be used in exception handling to report, or, store in an error log table, the error that occurred in the code. These are especially useful for the WHEN OTHERS exception.

What are the Back ground processes in Oracle and what are they?
There are basically 9 Processes.They do the house keeping activities for the Oracle and are common in any system.The various background processes in oracle are:

a) Data Base Writer(DBWR) :: Data Base Writer Writes Modified blocks from Database buffer cache to Data Files.This is required since the data is not written whenever a transaction is committed.

b) LogWriter(LGWR) :: Log Writer writes the redo log entries to disk. Redo Log data is generated in redo log buffer of SGA. As transaction commits and log buffer fills, LGWR writes log entries into a online redo log file.

c) System Monitor(SMON) :: The System Monitor performs instance recovery at instance start up.This is useful for recovery from system failure.

d) Process Monitor(PMON) :: The Process Monitor peforms process recovery when user Process fails. Pmon Clears and Frees resources that process was using.

e) CheckPoint(CKPT) :: At Specified times, all modified database buffers in SGA are written to data files by DBWR at Checkpoints and Updating all data files and control files of database to indicate the most recent checkpoint.

f) Archieves(ARCH) :: The Archiver copies online redo log files to archival storal when they are busy.

g) Recoveror(RECO) :: The Recoveror is used to resolve the distributed transaction in network.

h) Dispatcher (Dnnn) :: The Dispatcher is useful in Multi Threaded Architecture.

i)  Lckn :: We can have upto 10 lock processes for inter instance locking in parallel sql.

How many types of Sql Statements are there in Oracle?
There are basically 6 types of sql statments.They are
a) Data Definition Language(DDL) :: The DDL statments define and maintain objects and drop objects.

b) Data Manipulation Language(DML) :: The DML statements manipulate database data.

c) Transaction Control Statements :: Manage change by DML

d) Session Control :: Used to control the properties of current session enabling and disabling roles and changing .e.g, Alter Statements,Set Role

e) System Control Statements :: Change Properties of Oracle Instance .e.g, Alter System.

f) Embedded Sql :: Incorporate DDL, DML and T.C.S in Programming Language.e.g, Using the Sql Statements in languages such as 'C', Open,Fetch, execute and close

What is a Transaction in Oracle?
A transaction is a Logical unit of work that compromises one or more SQL Statements executed by a single User. According to ANSI, a transaction begins with first executable statement and ends when it is explicitly committed or rolled back.

Key Words Used in Oracle?
The Key words that are used in Oracle are ::
a) Commiting :: A transaction is said to be commited when the transaction makes permanent changes resulting from the SQL statements.

b) Rollback :: A transaction that retracts any of the changes resulting from SQL statements in Transaction.

c) SavePoint :: For long transactions that contain many SQL statements, intermediate markers or savepoints are declared. Savepoints can be used to divide a transactino into smaller points.

d) Rolling Forward :: Process of applying redo log during recovery is called rolling forward.

e) Cursor :: A cursor is a handle ( name or a pointer) for the memory associated with a specific stament. A cursor is basically an area allocated by Oracle for executing the Sql Statement. Oracle uses an implicit cursor statement for Single row query and Uses Explcit cursor for a multi row query.

f) System Global Area(SGA) :: The SGA is a shared memory region allocated by the Oracle that contains Data and control information for one Oracle Instance.It consists of Database Buffer Cache and Redo log Buffer.

g) Program Global Area (PGA) :: The PGA is a memory buffer that contains data and control information for server process.

g) Database Buffer Cache :: Database Buffer of SGA stores the most recently used blocks of database data.The set of database buffers in an instance is called Database Buffer Cache.

h) Redo log Buffer :: Redo log Buffer of SGA stores all the redo log entries.

i) Redo Log Files :: Redo log files are set of files that protect altered database data in memory that has not been written to Data Files. They are basically used for backup when a database crashes.

j) Process :: A Process is a 'thread of control' or mechansim in Operating System that executes series of steps.

What are Procedure,functions and Packages?
* Procedures and functions consist of set of PL/SQL statements that are grouped together as a unit to solve a specific problem or perform set of related tasks.
* Procedures do not Return values while Functions return one One Value
*Packages :: Packages Provide a method of encapsulating and storing related procedures, functions, variables and other Package Contents

What are Database Triggers and Stored Procedures?
Database Triggers :: Database Triggers are Procedures that are automatically executed as a result of insert in, update to, or delete from table. Database triggers have the values old and new to denote the old value in the table before it is deleted and the new indicated the new value that will be used. DT are useful for implementing complex business rules which cannot be enforced using the integrity rules.We can have the trigger as Before trigger or After Trigger and at Statement or Row level.

e.g:: operations insert,update ,delete 3
before ,after 3*2 A total of 6 combinations

At statement level(once for the trigger) or row level( for every execution ) 6 * 2 A total of 12.

Thus a total of 12 combinations are there and the restriction of usage of 12 triggers has been lifted from Oracle 7.3 Onwards.

Stored Procedures :: Stored Procedures are Procedures that are stored in Compiled form in the database.The advantage of using the stored procedures is that many users can use the same procedure in compiled and ready to use format.

How many Integrity Rules are there and what are they?
There are Three Integrity Rules. They are as follows ::
a) Entity Integrity Rule :: The Entity Integrity Rule enforces that the Primary key cannot be Null

b) Foreign Key Integrity Rule :: The FKIR denotes that the relationship between the foreign key and the primary key has to be enforced.When there is data in Child Tables the Master tables cannot be deleted.

c) Business Integrity Rules :: The Third Intigrity rule is about the complex business processes which cannot be implemented by the above 2 rules.

What are the Various Master and Detail Relation ships?
The various Master and Detail Relationship are

a) Non Isolated :: The Master cannot be deleted when a child is existing
b) Isolated :: The Master can be deleted when the child is existing
c) Cascading :: The child gets deleted when the Master is deleted.

What are the Various Block Coordination Properties?
The various Block Coordination Properties are

a) Immediate
Default Setting. The Detail records are shown when the Master Record are shown.

b) Defferred with Auto Query
Oracle Forms defer fetching the detail records until the operator navigates to the detail block.

c) Defferred with No Auto Query
The operator must navigate to the detail block and explicitly execute a query

What are the Different Optimization Techniques?
The Various Optimization techniques are

a) Execute Plan :: we can see the plan of the query and change it accordingly based on the indexes

b) Optimizer_hint ::
Select /*+ First_Rows */ Deptno,Dname,Loc,Rowid from dept
where (Deptno > 25)

c) Optimize_Sql ::
By setting the Optimize_Sql = No, Oracle Forms assigns a single cursor for all SQL statements.This slow downs the processing because for evertime the SQL must be parsed whenever they are executed.
f45run module = my_firstform userid = scott/tiger optimize_sql = No

d) Optimize_Tp ::
By setting the Optimize_Tp= No, Oracle Forms assigns seperate cursor only for each query SELECT statement. All other SQL statements reuse the cursor.
f45run module = my_firstform userid = scott/tiger optimize_Tp = No

Restrict '&' in Sql*Plus
sql> set define off
This will restrict the use of '&' in the sql*plus for that particular session


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