Interview Questions

Constraints enable the RDBMS to enforce the integrity of the database automatically, without the need to create triggers, rule or defaults.

Types of Constraints: NOT NULL, CHEQUE, UNIQUE, PRIMARY KEY, FOREIGN KEY.

Example:

"I have several awesome  achievements in my career. Probably the most awesome achievements were the delivery of the most recent version replace update to one of our core products for customer bills. This was a 1-year project and I was one of 9 team members. What made it more for me was that my role expanded from being one of the tech team individuals to taking the lead on building the mobile makings of the product. In order to deliver this aspect of the product, I pulled in 3 new project resources with new specific skills in each of the mobile technology floors we targeted and cross-trained all project resources to support each floor. In the last, our team delivered the product on time and have received numerous accolades, both external and internal. The mobile component was particularly  identified to be world class and distributed the product at its release. Our CEO spent time showing the mobile components to the industry and press and it has since met with superb  reviews. Would you like to see the Android version of the product?"

The following are the areas of concern for tuning:

- Memory Usage

- Data Storage

- Data Manipulation

- Physical Storage

- Logic Storage

- Network Traffic

Tuning Memory Usage: In Oracle 10g, we can use the Automatic Workload Repository (AWR) toolset to gather and manage statistical data but in case of Oracle 11g, we can use new initialization parameters such as MEMORY_TARGET to further control the overall memory used by Oracle. It helps us to tune the database automatically when we don’t have time to read the AWR report.

Tuning Data Manipulation: There are two ways to tune Data manipulation in Oracle one way is through Conventional Path mode and second is Direct Path mode.

Tuning Physical Storage: We need to tune the physical storage because it limits the disk in database. This can be done by: Distributing I/O, Striping and Mirroring.

Primary key constraint ensures that the column(s) always has a unique value to identify the record.
Example:
Below, the primary key is created for column id with name prim_id.
create table employee ( id number NOT NULL, Name varchar(200) Constraint prim_id primary key(id) );

ABAP Editor: Tool in the ABAP Workbench in which you enter the source code of ABAP programs and check their syntax. You can also navigate from the ABAP Editor to the other tools in the ABAP Workbench.

array_flip exchange the keys with their associated values in array ie. Keys becomes values and values becomes keys.

<?php
$arrayName    = array("course1"=>"php","course2"=>"html");
$new_array    = array_flip($arrayName);
print_r($new_array);
?>

OUTPUT :

Array
(
[php]     => course1
[html]    => course2
)

The intention of the interviewer by asking this question is to discover the pain points for the candidate.

Here this can be explained with an example like this :

The administrative assistant might seem like someone whose job is simply keeping everything filed and organized and scheduled. But they actually are the building block of the entire office, making everyone's lives function more smoothly and with good access to information when they need it.

Sometimes I have so many things crossing my desk at a given time that I can get a bit overwhelmed. When this happens I take a deep breath and focus on prioritizing the work. Then I get a clear head again and can dive back in.

Value type :

• Stores the data


• The value of value types is stored on the managed stack


• They are lighter objects 


• One variable can have only one value

Reference Type :

• Stores the reference to the data


• A reference type is allocated on the heap


• They are heavier objects


• Several variables can reference the same data