In PL/SQL (Procedural Language/Structured Query Language), sequential control refers to the order in which statements are executed in a block of code. Sequential control in PL/SQL is managed by the flow control statements, which determine the order in which the program’s statements are executed. These statements include:
Sequential Execution:
PL/SQL code is executed sequentially, line by line, unless directed otherwise by control flow statements. This means that each statement is executed in the order it appears in the code.
DECLARE x NUMBER := 10; y NUMBER := 20; z NUMBER; BEGIN z := x + y; -- Executed sequentially END;
Conditional Statements:
Conditional statements, such as IF-THEN-ELSE, control the flow of execution based on a specified condition. The program will follow different paths depending on whether the condition is true or false.
DECLARE
x NUMBER := 10;
BEGIN
IF x > 5 THEN
DBMS_OUTPUT.PUT_LINE('x is greater than 5');
ELSE
DBMS_OUTPUT.PUT_LINE('x is not greater than 5');
END IF;
END;
Loop Statements:
Loop statements, such as FOR and WHILE loops, enable repetitive execution of a block of code. The loop continues until a specified condition is met.
DECLARE
i NUMBER;
BEGIN
FOR i IN 1..5 LOOP
DBMS_OUTPUT.PUT_LINE('Iteration ' || i);
END LOOP;
END;
GOTO Statement:
The GOTO statement allows jumping to a labeled statement within the code. While the use of GOTO is generally discouraged in structured programming, it can be employed in certain scenarios.
DECLARE
x NUMBER := 10;
BEGIN
IF x > 5 THEN
GOTO label1;
END IF;
DBMS_OUTPUT.PUT_LINE('This line is skipped if x is greater than 5');
<<label1>>
DBMS_OUTPUT.PUT_LINE('This line is executed if x is greater than 5');
END;
It’s important to note that well-structured and modular code is preferred over excessive use of GOTO statements, as it enhances code readability and maintainability. Developers should use control flow statements judiciously to create efficient and logically organized PL/SQL programs.