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ASSIGNMENT OF

DBMS

Submitted to: Submitted by:

Ms. Pency Juneja Rohit Nagpal

Roll no.

B44

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Part A

Q1 - Explain explicit cursor handling with diagram?

ANS: When in dividend records in a table have to be processed in a side a PL/SQL code block

cursor icon used. This cursor will be declared and mapped to in SQL query in the declare section

at the PL/SQL block and used within the executable section. A curser thus created and used is

known as explicit cursor.

CURSOR DECLERATION:-

SYNTAX: Cursor cursor_name IS SQL SELECT statement;

OPENING A CURSOR

SYNTAX: Open cursor_name;

FETCHING RECORD FORM A CURSOR

SYNTAX: Fetch cursor_name INTO var1;

CLOSING A CURSOR

SYNTAX: Close cursor_name;

DIAGRAM:

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Enforce complex business rules.

Provide transparent event logging.

Provide sophisticated auditing.

Maintain synchronous table replicates.

Gather statistics on table access.

Part B

Q4 -Explain syntax with example for loops, while loop?

ANS-: A while loop is a control flow statement that allows code to be executed repeatedly based

on a given Boolean condition. The while loop can be thought of as a repeating if statement.

The while construct consists of a block of code and a condition. The condition is evaluated, and

if the condition is true, the code within the block is executed. This repeats until the condition

becomes false. Because whileloops check the condition before the block is executed, the control

structure is often also known as a pre-test loop. Compare with the do while loop, which tests the

condition after the loop has executed.

Syntax for the WHILE Loop is:

WHILE

LOOP

END LOOP;

You would use a WHILE Loop when you are not sure how many times you will execute the loop

body. Since the WHILE condition is evaluated before entering the loop, it is possible that the

loop body may not execute even once.

EXAMPLE:-

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WHILE monthly_value

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DBMS_output.put_line (the inverted number is||inverted_number);

END;

total_val:= total_val + employee_rec.monthly_income;

END LOOP;RETURN total_val;

END;

Q5 -Explain syntax with example if and then loop?

ANS: SYNTAX: - IF

IF THEN

ELSE IF THEN

ELSE

END IF;

EXAMPLE:-

Write a PL/SQL code block that will accept an account no. from the user & debit an amount of

rupees 2000 from the account if the account has a minimum of rs 500 after the amount is debited

the process is to be fired on the account table.

DECLARE

Account_balance number (11,2);

Account_number varchar 2 (0);

Debit_amount_number (5):=2000;

Min_balance constant number (5, 2):=500.00

BEGIN

Account_number:=&account number;

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SELECT balance into account_balance from accounts where

account_id=account_number;

Account_balance:=account_balance debit_amount;

If account_balance>= min_balance Then

Update account set balance= balance debit_amount

Where account = id = account_number;

END IF;

END;

Q6 -Explain the PL/SQL languages elements?

ANS: PL/SQL Language has total 52 Elements. Some of the Pl/SQL elements are:

Assignment Statement

An assignment statement sets the current value of a variable, field, parameter, or element. The

statement consists of an assignment target followed by the assignment operator and an

expression. When the statement is executed, the expression is evaluated and the resulting value is

stored in the target.

AUTONOMOUS_TRANSACTION Pragma

The AUTONOMOUS_TRANSACTION pragma changes the way a subprogram works within a

transaction. A subprogram marked with this pragma can do SQL operations and commit or roll

back those operations, without committing or rolling back the data in the main transaction.

Block Declaration

The basic program unit in PL/SQL is the block. A PL/SQL block is defined by the keywords

DECLARE, BEGIN, EXCEPTION, and END. These keywords partition the block into a

declarative part, an executable part, and an exception-handling part. Only the executable part is

required. You can nest a block within another block wherever you can place an executable

statement.

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CASE Statement

The CASE statement chooses from a sequence of conditions, and executes a corresponding

statement. The CASE statement evaluates a single expression and compares it against several

potential values, or evaluates multiple Boolean expressions and chooses the first one that is

TRUE.

CLOSE Statement

The CLOSE statement indicates that you are finished fetching from a cursor or cursor variable,

and that the resources held by the cursor can be reused.

Collection Definition

A collection is an ordered group of elements, all of the same type. For example, the grades for a

class of students. Each element has a unique subscript that determines its position in the

collection. PL/SQL offers three kinds of collections: associative arrays, nested tables, and

varrays (short for variable-size arrays). Nested tables extend the functionality of associative

arrays (formerly called PL/SQL tables or index-by tables).

Collections work like the arrays found in most third-generation programming languages.

Collections can have only one dimension. Most collections are indexed by integers, althoughassociative arrays can also be indexed by strings. To model multi-dimensional arrays, you can

declare collections whose items are other collections.

Nested tables and varrays can store instances of an object type and, conversely, can be attributes

of an object type. Collections can also be passed as parameters. You can use them to move

columns of data into and out of database tables or between client-side applications and stored

subprograms.

Collection Methods

A collection method is a built-in function or procedure that operates on collections and is called

using dot notation. You can use the methods EXISTS, COUNT, LIMIT, FIRST, LAST, PRIOR,

NEXT, EXTEND, TRIM, and DELETE to manage collections whose size is unknown or varies.

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EXISTS, COUNT, LIMIT, FIRST, LAST, PRIOR, and NEXT are functions that check the

properties of a collection or individual collection elements. EXTEND, TRIM, and DELETE are

procedures that modify a collection.

EXISTS, PRIOR, NEXT, TRIM, EXTEND, and DELETE take integer parameters. EXISTS,

PRIOR, NEXT, and DELETE can also take VARCHAR2 parameters for associative arrays withstring keys. EXTEND and TRIM cannot be used with index-by tables.

Comments

Comments let you include arbitrary text within your code to explain what the code does. You can

also disable obsolete or unfinished pieces of code by turning them into comments.

PL/SQL supports two comment styles: single-line and multi-line. A double hyphen (- -)

anywhere on a line (except within a character literal) turns the rest of the line into a comment.Multi-line comments begin with a slash-asterisk (/*) and end with an asterisk-slash (*/).