How to write a simple program using PL/SQL
In this section, we are going to write a simple program for printing “Hello World” using “Anonymous block“.
BEGIN
dbms_output.put_line (‘Hello World..');
END;
/
Output:
Hello World...
Code Explanation:
- Code line 2: Prints the message “Hello World. . .”
- The below screenshot explains how to enter the code in SQL* Plus.
Note: A block should be always followed by ‘/’ which sends the information to the compiler about the end of the block. Till the compiler encounters ‘/’, it will not consider the block is completed, and it will not execute it.
Declaring and usage of variables in the program
Here we are going to print the “Hello World” using the variables.
DECLARE
text VARCHAR2(25);
BEGIN
text:= ‘Hello World’;
dbms_output.put_line (text);
END:
/
Output:
Hello World
Code Explanation:
- Code line 2: Declaring a variable “text” of a VARCHAR2 type with size 25
- Code line 4: Assigning the value “Hello World” to the variable “text”.
- Code line 5: Printing the value of the variable “text”.
Comments in PL/SQL
Commenting code simply instructs the compiler to ignore that particular code from executing.
Comment can be used in the program to increase the readability of the program. In PL/SQL codes can be commented in two ways.
- Using ‘–‘ in the beginning of the line to comment that particular line.
- Using ‘/*…….*/’ we can use multiple lines. The symbol ‘/*’ marks the starting of the comment and the symbol ‘*/’ marks the end of the comment. The code between these two symbols will be treated as comments by the compiler.
Example: In this example, we are going to print ‘Hello World’ and we are also going to see how the commented lines behave in the code
BEGIN
--single line comment
dbms output.put line (' Hello World ’);
/*Multi line commenting begins
Multi line commenting ends */
END;
/
Output:
Hello World
Code Explanation:
- Code line 2: Single line comment and compiler ignored this line from execution.
- Code line 3: Printing the value “Hello World.”
- Code line 4: Multiline commenting starts with ‘/*’
- Code line 5: Multiline commenting ends with ‘*/’
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