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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