”;
In this chapter, we will discuss the DBMS Output in PL/SQL. The DBMS_OUTPUT is a built-in package that enables you to display output, debugging information, and send messages from PL/SQL blocks, subprograms, packages, and triggers. We have already used this package throughout our tutorial.
Let us look at a small code snippet that will display all the user tables in the database. Try it in your database to list down all the table names −
BEGIN
dbms_output.put_line (user || '' Tables in the database:'');
FOR t IN (SELECT table_name FROM user_tables)
LOOP
dbms_output.put_line(t.table_name);
END LOOP;
END;
/
DBMS_OUTPUT Subprograms
The DBMS_OUTPUT package has the following subprograms −
| S.No | Subprogram & Purpose | |
|---|---|---|
| 1 |
DBMS_OUTPUT.DISABLE; Disables message output. |
|
| 2 |
DBMS_OUTPUT.ENABLE(buffer_size IN INTEGER DEFAULT 20000); Enables message output. A NULL value of buffer_size represents unlimited buffer size. |
|
| 3 |
DBMS_OUTPUT.GET_LINE (line OUT VARCHAR2, status OUT INTEGER); Retrieves a single line of buffered information. |
|
| 4 |
DBMS_OUTPUT.GET_LINES (lines OUT CHARARR, numlines IN OUT INTEGER); Retrieves an array of lines from the buffer. |
|
| 5 |
DBMS_OUTPUT.NEW_LINE; Puts an end-of-line marker. |
|
| 6 |
DBMS_OUTPUT.PUT(item IN VARCHAR2); Places a partial line in the buffer. |
|
| 7 |
DBMS_OUTPUT.PUT_LINE(item IN VARCHAR2); Places a line in the buffer. |
Example
DECLARE
lines dbms_output.chararr;
num_lines number;
BEGIN
-- enable the buffer with default size 20000
dbms_output.enable;
dbms_output.put_line(''Hello Reader!'');
dbms_output.put_line(''Hope you have enjoyed the tutorials!'');
dbms_output.put_line(''Have a great time exploring pl/sql!'');
num_lines := 3;
dbms_output.get_lines(lines, num_lines);
FOR i IN 1..num_lines LOOP
dbms_output.put_line(lines(i));
END LOOP;
END;
/
When the above code is executed at the SQL prompt, it produces the following result −
Hello Reader! Hope you have enjoyed the tutorials! Have a great time exploring pl/sql! PL/SQL procedure successfully completed.
”;