Oracle - 36 - FOR Loop WHILE Loop IF-THEN-ELSE

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In Oracle PL/SQL, FOR loops, WHILE loops, and IF-THEN-ELSE statements are control structures used for flow control and conditional logic within code blocks. These constructs allow developers to create iterative processes and make decisions based on conditions. Here’s a brief description of each:

1. FOR Loop:

Purpose: The FOR loop is used for iterating over a specified range or collection of values a predefined number of times.

Syntax:

FOR loop_counter IN [REVERSE] start_value..end_value LOOP
— Loop body
END LOOP;

Use Cases: FOR loops are typically used when you know the exact number of iterations needed, such as iterating through a range of integers, processing elements in an array, or executing a block of code multiple times.

2. WHILE Loop:

Purpose: The WHILE loop is used for iterative processing based on a condition that is evaluated before each iteration.

Syntax:
WHILE condition LOOP
— Loop body
END LOOP;

Use Cases: WHILE loops are useful when you need to repeatedly execute a block of code as long as a specific condition remains true. The number of iterations can vary.

3. IF-THEN-ELSE:

Purpose: The IF-THEN-ELSE statement is used for conditional branching in PL/SQL programs. It allows you to execute different blocks of code based on a specified condition.

Syntax:

IF condition THEN
— Code to execute if the condition is true
[ELSIF condition2 THEN
— Code to execute if condition2 is true]
[ELSE
— Code to execute if no conditions are true]
END IF;

Use Cases: IF-THEN-ELSE statements are fundamental for making decisions within PL/SQL programs. They are used to control the flow of execution based on the evaluation of one or more conditions.

4. LOOP and EXIT:

Purpose: In addition to FOR and WHILE loops, PL/SQL provides a LOOP construct that allows you to create an indefinite loop. You can use the EXIT statement within loops to exit the loop when a specific condition is met.

Syntax:
LOOP
  -- Loop body
  EXIT WHEN condition; -- Exit condition
END LOOP;

Use Cases: LOOP and EXIT are useful when you need to perform a task repeatedly until a particular condition is satisfied. They offer flexibility for creating custom loop structures.

These control structures are essential for implementing flow control, conditional logic, and iterative processes within PL/SQL programs. Developers use them to create efficient, readable, and maintainable code that performs various tasks, ranging from data processing and validation to decision-making based on specific conditions.

Oracle – 36 – FOR Loop WHILE Loop IF-THEN-ELSE