PL/SQL – DBMS Output
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.
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