DBMS_OUTPUT in SQL Developer

Introduction

DBMS_OUTPUT is a built-in package in Oracle that allows the display of messages from PL/SQL procedures, functions, and anonymous blocks. The messages can be displayed in SQL Developer, as well as other integrated development environments (IDEs) and command-line interfaces.

Syntax

The basic syntax for using DBMS_OUTPUT in SQL Developer is as follows:

SET SERVEROUTPUT ON

DECLARE
  -- declare variables
BEGIN
  -- code block including DBMS_OUTPUT statements
END;
/

SET SERVEROUTPUT ON is used to enable the display of messages in SQL Developer.

The DECLARE statement is used to declare any necessary variables for the code block.

The code block includes the necessary code to produce the desired output, which is typically achieved through DBMS_OUTPUT.PUT_LINE() statements.

Example

Consider the following example, which calculates the average salary for a given department:

SET SERVEROUTPUT ON

DECLARE
  deptno NUMBER := 50;
  avg_sal NUMBER;
BEGIN
  SELECT AVG(sal) INTO avg_sal
  FROM emp
  WHERE deptno = deptno;
  
  DBMS_OUTPUT.PUT_LINE('The average salary for department ' || deptno || ' is ' || TO_CHAR(avg_sal));
END;
/

The output in SQL Developer would be:

The average salary for department 50 is 2175

Conclusion

DBMS_OUTPUT is a helpful tool for displaying messages from PL/SQL code blocks in SQL Developer. By using SET SERVEROUTPUT ON and DBMS_OUTPUT.PUT_LINE(), developers can easily display messages to aid in debugging, testing, and analysis.