6
Q:

Define Executive Plan in Database SQL ? 

Answer:



Q:

Foreign key in DBMS is

Answer

Foreign keys are the columns of a table that points to the primary key of another table. They act as a cross-reference between tables.


 


In detail : A Foreign key is a field (or collection of fields) in one table that uniquely identifies a row of another table or the same table. In simpler words, the foreign key is defined in a second table, but it refers to the primary key or a unique key in the first table.

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1 12
Q:

A Transparent DBMS

A) Keep its logical structure hidden from users B) Can access control
C) Keeps its physical structure hidden from users D) Can not hide sensitive information from users
 
Answer & Explanation Answer: C) Keeps its physical structure hidden from users

Explanation:

DBMS :: Database Managemet System.

A DBMS which keeps its physical structure hidden from the user is known as a transparent DBMS.

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2 41
Q:

What is Primary Key in DBMS?

Answer

A primary key is a special relational database table column or combination of columns designated to uniquely identify all table records. That is, A primary key is a column or set of columns in a table that uniquely identifies tuples (rows) in that table.


A primary key, also called a Primary Keyword.



Main Features Primary key are ::


It must contain a unique value for each row of data.


It cannot contain null values.

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10 68
Q:

what will be the output of the following code?

class Value
{
    public int i = 15;
}
public class Test
{
    public static void main(String argv[])
    {
        Test t = new Test();
        t.first();
    }
    public void first()
    {
        int i = 5;
        Value v = new Value();
        v.i = 25;
        second(v, i);
        System.out.println(v.i);
    }
    public void second(Value v, int i)
    {
        i = 0;
        v.i = 20;
        Value val = new Value();
        v =  val;
        System.out.println(v.i + " " + i);
    }
}

A) 15 0 2 B) 15 0 0
C) 15 20 0 D) 15 0 20
 
Answer & Explanation Answer: D) 15 0 20

Explanation:
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3 69
Q:

Difference between Candidate key and Primary key?

Answer

Candidate Key – A Candidate Key can be any column or a combination of columns that can qualify as unique key in database. There can be multiple Candidate Keys in one table. Each Candidate Key can qualify as Primary Key. 


Primary Key – A Primary Key is a column or a combination of columns that uniquely identify a record. Only one Candidate Key can be Primary Key.






        • One needs to be very careful in selecting the Primary Key as an incorrect selection can adversely impact the database architect and future normalization. For a Candidate Key to qualify as a Primary Key, it should be Non-NULL and unique in any domain.




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6 122
Q:

Which dml command is used in conjunction with @@identity?

A) INSERT and UPDATE B) UPDATE and DELETE
C) SCOPE_IDENTITY and IDENT_CURRENT D) Commit and rollback
 
Answer & Explanation Answer: C) SCOPE_IDENTITY and IDENT_CURRENT

Explanation:

Using automatically incrementing IDENTITY columns is very popular with database developers. You don’t need to explicitly calculate unique surrogate keys when inserting new data, the IDENTITY column functionality does that for you. The IDENTITY feature also allows you to specify useful Seed and Increment properties. When you use an INSERT statement to insert data into a table with an IDENTITY column defined, SQL Server will generate a new IDENTITY value.

 

You can use the @@IDENTITY variable and the SCOPE_IDENTITY and IDENT_CURRENT functions to return the last IDENTITY value that has been generated by SQL Server. This is very useful when you need to return the key for the row that has just been inserted, back to the caller.

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5 190
Q:

Why do you need common fields in a Database?

Answer

A database that contains multiple tables related through common fields.


A common field is a field of data that is shared among all forms in a database. Without them, it would be difficult and/or time-consuming to create other forms.

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6 88
Q:

MOV extension refers to what files?

A) Audio B) Movies or other Videos
C) Images D) Documents
 
Answer & Explanation Answer: B) Movies or other Videos

Explanation:

A .MOV file is a common multimedia container file format developed by Apple. It may contain multiple tracks that store different types of media data and is often used for saving movies and other video files.

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3 71