PL/SQL - Programming Language (MCQ) questions

1)   Which operators combine the results of two queries into one result? (PL/SQL)
- Published on 26 Jun 15

a. Set operator
b. Row Operator
c. Both A & B
d. None of the above
Answer  Explanation 

ANSWER: Set operator

Explanation:
The set operators combines the results of two queries into a single result. Queries which contain these set operators are known as compound queries.


2)   Which of the following returns the current value in a specified sequence. (PL/SQL)
- Published on 26 Jun 15

a. CURRVAL
b. NEXTVAL
c. Both A & B
d. None of the above
Answer  Explanation 

ANSWER: CURRVAL

Explanation:
The CURRVAL returns the current value of the sequence.


3)   “NO_DATA_FOUND” and “TOO_MANY_ROWS” are the two most common errors found when executing a SELECT statement. (PL/SQL)
- Published on 26 Jun 15

a. True
b. False
Answer  Explanation 

ANSWER: True

Explanation:
The “NO_DATA_FOUND” error is where the program is not able to find any data. This type of error can be trapped by the exception block.
The “TOO_MANY_ROWS” error is where one row data is conflicting with another row data so it is unable to fetch a particular data. This error too can be trapped by the exception block.


4)   In PL/SQL, a warning or error condition is called an exception.
- Published on 26 Jun 15

a. True
b. False
Answer  Explanation 

ANSWER: True

Explanation:
An error condition during a program is known as an exception. The exception block is used in the program and an appropriate action is taken against the error condition.
There are 2 types of exceptions
1. System-defined exceptions
2. User-defined exceptions.


5)   The comparison methods are used for comparing objects. How many ways are available for comparing objects? (PL/SQL)
- Published on 26 Jun 15

a. 4
b. 1
c. 2
d. 5
Answer  Explanation 

ANSWER: 2

Explanation:
The 2 methods used for comparing objects are
Map Method- It is a function implemented in such a way that its values depends depends upon the value of the attributes

Order Method- It implements some internal logic for comparing two objects.


6)   Nested tables are a good choice when -
(PL/SQL)

- Published on 26 Jun 15

a. The index values are not consecutive.
b. There is no set number of index values. However, a maximum limit is imposed.
c. You need to delete or update some elements, but not all the elements at once.
d. You would usually create a separate lookup table, with multiple entries for each row of the main table, and access it through join queries.
e. All mentioned above
Answer  Explanation 

ANSWER: All mentioned above

Explanation:
A nested table is similar to index by table but it can be stored in the database columns. It can be considered as a single column table that can either be in a memory or as a column in a database table. The elements can be deleted or added anywhere in a nested table. It may even contain empty elements.


7)   PL/SQL: The DBMS_SQL package should be used in which of the following situations?
- Published on 24 Jun 15

a. 13. There is an unknown number of input or output variables, such as the number of column values returned by a query, that are used in a dynamic SQL statement.
b. The dynamic code is too large to fit inside a 32K bytes VARCHAR2 variable.
c. Both A & B
d. None of the above
Answer  Explanation 

ANSWER: Both A & B

Explanation:
The DBMS_SQL package provides an interface to use dynamic SQL to parse any data manipulation language (DML) or data definition language (DDL) statement using PL/SQL


8)   PL/SQL: Dynamic SQL enables you to build SQL statements dynamically at runtime.
- Published on 24 Jun 15

a. True
b. False
Answer  Explanation 

ANSWER: True

Explanation:
Dynamic SQL helps to write programs that refer SQL statements whose full text is not known until the runtime.


9)   PL/SQL: SIGNTYPE lets you restrict an integer variable to the values -1, 0, and 1, which is useful in programming tri-state logic.
- Published on 24 Jun 15

a. True
b. False
Answer  Explanation 

ANSWER: True

Explanation:
Signtype is a subtype of binary integer. It requires less storage.


10)   PL/SQL: Is it possible to define a NOT NULL field in a record?
- Published on 24 Jun 15

a. Yes
b. No
Answer  Explanation 

ANSWER: Yes

Explanation:
The not null field helps us return all the not null records. It is like giving a condition to the block or the expression.


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