Postgres Plus Advanced Server Oracle Compatibility Developer's Guide : 7.4 DBMS_OUTPUT

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Postgres Plus Advanced Server Oracle Compatibility Developer's Guide

 

7.4 DBMS_OUTPUT

The DBMS_OUTPUT package provides the capability to send messages (lines of text) to a message buffer, or get messages from the message buffer. A message buffer is local to a single session. Use the DBMS_PIPE package to send messages between sessions.

The procedures and functions available in the DBMS_OUTPUT package are listed in the following table.

Table 7-7-5 DBMS_OUTPUT Functions/Procedures

Function/Procedure

Return Type

Description

DISABLE

n/a

Disable the capability to send and receive messages.

ENABLE(buffer_size)

n/a

Enable the capability to send and receive messages.

GET_LINE(line OUT, status OUT)

n/a

Get a line from the message buffer.

GET_LINES(lines OUT, numlines IN OUT)

n/a

Get multiple lines from the message buffer.

NEW_LINE

n/a

Puts an end-of-line character sequence.

PUT(item)

n/a

Puts a partial line without an end-of-line character sequence.

PUT_LINE(item)

n/a

Puts a complete line with an end-of-line character sequence.

SERVEROUTPUT(stdout)

n/a

Direct messages from PUT, PUT_LINE, or NEW_LINE to either standard output or the message buffer.

The following table lists the public variables available in the DBMS_OUTPUT package.

Table 7-7-6 DBMS_OUTPUT Public Variables

Public Variables

Data Type

Value

Description

chararr

TABLE

 

For message lines.

7.4.1 CHARARR

The CHARARR is for storing multiple message lines.

TYPE chararr IS TABLE OF VARCHAR2(32767) INDEX BY BINARY_INTEGER;

7.4.2 DISABLE

The DISABLE procedure clears out the message buffer. Any messages in the buffer at the time the DISABLE procedure is executed will no longer be accessible. Any messages subsequently sent with the PUT, PUT_LINE, or NEW_LINE procedures are discarded. No error is returned to the sender when the PUT, PUT_LINE, or NEW_LINE procedures are executed and messages have been disabled.

Use the ENABLE procedure or SERVEROUTPUT(TRUE) procedure to re-enable the sending and receiving of messages.

DISABLE

Examples

This anonymous block disables the sending and receiving messages in the current session.

BEGIN
    DBMS_OUTPUT.DISABLE;
END;

7.4.3 ENABLE

The ENABLE procedure enables the capability to send messages to the message buffer or retrieve messages from the message buffer. Running SERVEROUTPUT(TRUE) also implicitly performs the ENABLE procedure.

The destination of a message sent with PUT, PUT_LINE, or NEW_LINE depends upon the state of SERVEROUTPUT.

    ● If the last state of SERVEROUTPUT is TRUE, the message goes to standard output of the command line.

    ● If the last state of SERVEROUTPUT is FALSE, the message goes to the message buffer.

ENABLE [ (buffer_size INTEGER) ]

Parameters

buffer_size

Maximum length of the message buffer in bytes. If a buffer_size of less than 2000 is specified, the buffer size is set to 2000.

Examples

The following anonymous block enables messages. Setting SERVEROUTPUT(TRUE) forces them to standard output.

BEGIN
    DBMS_OUTPUT.ENABLE;
    DBMS_OUTPUT.SERVEROUTPUT(TRUE);
    DBMS_OUTPUT.PUT_LINE('Messages enabled');
END;

Messages enabled

The same effect could have been achieved by simply using SERVEROUTPUT(TRUE).

BEGIN
    DBMS_OUTPUT.SERVEROUTPUT(TRUE);
    DBMS_OUTPUT.PUT_LINE('Messages enabled');
END;

Messages enabled

The following anonymous block enables messages, but setting SERVEROUTPUT(FALSE) directs messages to the message buffer.

BEGIN
    DBMS_OUTPUT.ENABLE;
    DBMS_OUTPUT.SERVEROUTPUT(FALSE);
    DBMS_OUTPUT.PUT_LINE('Message sent to buffer');
END;

7.4.4 GET_LINE

The GET_LINE procedure provides the capability to retrieve a line of text from the message buffer. Only text that has been terminated by an end-of-line character sequence is retrieved – that is complete lines generated using PUT_LINE, or by a series of PUT calls followed by a NEW_LINE call.

GET_LINE(line OUT VARCHAR2, status OUT INTEGER)

Parameters

line

Variable receiving the line of text from the message buffer.

status

0 if a line was returned from the message buffer, 1 if there was no line to return.

Examples

The following anonymous block writes the emp table out to the message buffer as a comma-delimited string for each row.

EXEC DBMS_OUTPUT.SERVEROUTPUT(FALSE);

DECLARE
    v_emprec        VARCHAR2(120);
    CURSOR emp_cur IS SELECT * FROM emp ORDER BY empno;
BEGIN
    DBMS_OUTPUT.ENABLE;
    FOR i IN emp_cur LOOP
        v_emprec := i.empno || ',' || i.ename || ',' || i.job || ',' ||
            NVL(LTRIM(TO_CHAR(i.mgr,'9999')),'') || ',' || i.hiredate ||
            ',' || i.sal || ',' ||
            NVL(LTRIM(TO_CHAR(i.comm,'9990.99')),'') || ',' || i.deptno;
        DBMS_OUTPUT.PUT_LINE(v_emprec);
    END LOOP;
END;

The following anonymous block reads the message buffer and inserts the messages written by the prior example into a table named messages. The rows in messages are then displayed.

CREATE TABLE messages (
    status          INTEGER,
    msg             VARCHAR2(100)
);

DECLARE
    v_line          VARCHAR2(100);
    v_status        INTEGER := 0;
BEGIN
    DBMS_OUTPUT.GET_LINE(v_line,v_status);
    WHILE v_status = 0 LOOP
        INSERT INTO messages VALUES(v_status, v_line);
        DBMS_OUTPUT.GET_LINE(v_line,v_status);
    END LOOP;
END;

SELECT msg FROM messages;

                               msg
-----------------------------------------------------------------
 7369,SMITH,CLERK,7902,17-DEC-80 00:00:00,800.00,,20
 7499,ALLEN,SALESMAN,7698,20-FEB-81 00:00:00,1600.00,300.00,30
 7521,WARD,SALESMAN,7698,22-FEB-81 00:00:00,1250.00,500.00,30
 7566,JONES,MANAGER,7839,02-APR-81 00:00:00,2975.00,,20
 7654,MARTIN,SALESMAN,7698,28-SEP-81 00:00:00,1250.00,1400.00,30
 7698,BLAKE,MANAGER,7839,01-MAY-81 00:00:00,2850.00,,30
 7782,CLARK,MANAGER,7839,09-JUN-81 00:00:00,2450.00,,10
 7788,SCOTT,ANALYST,7566,19-APR-87 00:00:00,3000.00,,20
 7839,KING,PRESIDENT,,17-NOV-81 00:00:00,5000.00,,10
 7844,TURNER,SALESMAN,7698,08-SEP-81 00:00:00,1500.00,0.00,30
 7876,ADAMS,CLERK,7788,23-MAY-87 00:00:00,1100.00,,20
 7900,JAMES,CLERK,7698,03-DEC-81 00:00:00,950.00,,30
 7902,FORD,ANALYST,7566,03-DEC-81 00:00:00,3000.00,,20
 7934,MILLER,CLERK,7782,23-JAN-82 00:00:00,1300.00,,10
(14 rows)

7.4.5 GET_LINES

The GET_LINES procedure provides the capability to retrieve one or more lines of text from the message buffer into a collection. Only text that has been terminated by an end-of-line character sequence is retrieved – that is complete lines generated using PUT_LINE, or by a series of PUT calls followed by a NEW_LINE call.

GET_LINES(lines OUT CHARARR, numlines IN OUT INTEGER)

Parameters

lines

      Table receiving the lines of text from the message buffer. See CHARARR for a description of lines.

numlines IN

Number of lines to be retrieved from the message buffer.

numlines OUT

Actual number of lines retrieved from the message buffer. If the output value of numlines is less than the input value, then there are no more lines left in the message buffer.

Examples

The following examples uses the GET_LINES procedure to store all rows from the emp table that were placed on the message buffer, into an array.

EXEC DBMS_OUTPUT.SERVEROUTPUT(FALSE);

DECLARE
    v_emprec        VARCHAR2(120);
    CURSOR emp_cur IS SELECT * FROM emp ORDER BY empno;
BEGIN
    DBMS_OUTPUT.ENABLE;
    FOR i IN emp_cur LOOP
        v_emprec := i.empno || ',' || i.ename || ',' || i.job || ',' ||
            NVL(LTRIM(TO_CHAR(i.mgr,'9999')),'') || ',' || i.hiredate ||
            ',' || i.sal || ',' ||
            NVL(LTRIM(TO_CHAR(i.comm,'9990.99')),'') || ',' || i.deptno;
        DBMS_OUTPUT.PUT_LINE(v_emprec);
    END LOOP;
END;

DECLARE
    v_lines         DBMS_OUTPUT.CHARARR;
    v_numlines      INTEGER := 14;
    v_status        INTEGER := 0;
BEGIN
    DBMS_OUTPUT.GET_LINES(v_lines,v_numlines);
    FOR i IN 1..v_numlines LOOP
        INSERT INTO messages VALUES(v_numlines, v_lines(i));
    END LOOP;
END;

SELECT msg FROM messages;

                               msg
-----------------------------------------------------------------
 7369,SMITH,CLERK,7902,17-DEC-80 00:00:00,800.00,,20
 7499,ALLEN,SALESMAN,7698,20-FEB-81 00:00:00,1600.00,300.00,30
 7521,WARD,SALESMAN,7698,22-FEB-81 00:00:00,1250.00,500.00,30
 7566,JONES,MANAGER,7839,02-APR-81 00:00:00,2975.00,,20
 7654,MARTIN,SALESMAN,7698,28-SEP-81 00:00:00,1250.00,1400.00,30
 7698,BLAKE,MANAGER,7839,01-MAY-81 00:00:00,2850.00,,30
 7782,CLARK,MANAGER,7839,09-JUN-81 00:00:00,2450.00,,10
 7788,SCOTT,ANALYST,7566,19-APR-87 00:00:00,3000.00,,20
 7839,KING,PRESIDENT,,17-NOV-81 00:00:00,5000.00,,10
 7844,TURNER,SALESMAN,7698,08-SEP-81 00:00:00,1500.00,0.00,30
 7876,ADAMS,CLERK,7788,23-MAY-87 00:00:00,1100.00,,20
 7900,JAMES,CLERK,7698,03-DEC-81 00:00:00,950.00,,30
 7902,FORD,ANALYST,7566,03-DEC-81 00:00:00,3000.00,,20
 7934,MILLER,CLERK,7782,23-JAN-82 00:00:00,1300.00,,10
(14 rows)

7.4.6 NEW_LINE

The NEW_LINE procedure writes an end-of-line character sequence in the message buffer.

NEW_LINE

Parameters

The NEW_LINE procedure expects no parameters.

7.4.7 PUT

The PUT procedure writes a string to the message buffer. No end-of-line character sequence is written at the end of the string. Use the NEW_LINE procedure to add an end-of-line character sequence.

PUT(item VARCHAR2)

Parameters

item

Text written to the message buffer.

Examples

The following example uses the PUT procedure to display a comma-delimited list of employees from the emp table.

DECLARE
    CURSOR emp_cur IS SELECT * FROM emp ORDER BY empno;
BEGIN
    FOR i IN emp_cur LOOP
        DBMS_OUTPUT.PUT(i.empno);
        DBMS_OUTPUT.PUT(',');
        DBMS_OUTPUT.PUT(i.ename);
        DBMS_OUTPUT.PUT(',');
        DBMS_OUTPUT.PUT(i.job);
        DBMS_OUTPUT.PUT(',');
        DBMS_OUTPUT.PUT(i.mgr);
        DBMS_OUTPUT.PUT(',');
        DBMS_OUTPUT.PUT(i.hiredate);
        DBMS_OUTPUT.PUT(',');
        DBMS_OUTPUT.PUT(i.sal);
        DBMS_OUTPUT.PUT(',');
        DBMS_OUTPUT.PUT(i.comm);
        DBMS_OUTPUT.PUT(',');
        DBMS_OUTPUT.PUT(i.deptno);
        DBMS_OUTPUT.NEW_LINE;
    END LOOP;
END;

7369,SMITH,CLERK,7902,17-DEC-80 00:00:00,800.00,,20
7499,ALLEN,SALESMAN,7698,20-FEB-81 00:00:00,1600.00,300.00,30
7521,WARD,SALESMAN,7698,22-FEB-81 00:00:00,1250.00,500.00,30
7566,JONES,MANAGER,7839,02-APR-81 00:00:00,2975.00,,20
7654,MARTIN,SALESMAN,7698,28-SEP-81 00:00:00,1250.00,1400.00,30
7698,BLAKE,MANAGER,7839,01-MAY-81 00:00:00,2850.00,,30
7782,CLARK,MANAGER,7839,09-JUN-81 00:00:00,2450.00,,10
7788,SCOTT,ANALYST,7566,19-APR-87 00:00:00,3000.00,,20
7839,KING,PRESIDENT,,17-NOV-81 00:00:00,5000.00,,10
7844,TURNER,SALESMAN,7698,08-SEP-81 00:00:00,1500.00,0.00,30
7876,ADAMS,CLERK,7788,23-MAY-87 00:00:00,1100.00,,20
7900,JAMES,CLERK,7698,03-DEC-81 00:00:00,950.00,,30
7902,FORD,ANALYST,7566,03-DEC-81 00:00:00,3000.00,,20
7934,MILLER,CLERK,7782,23-JAN-82 00:00:00,1300.00,,10

7.4.8 PUT_LINE

The PUT_LINE procedure writes a single line to the message buffer including an end-of-line character sequence.

PUT_LINE(item VARCHAR2)

Parameters

item

Text to be written to the message buffer.

Examples

The following example uses the PUT_LINE procedure to display a comma-delimited list of employees from the emp table.

DECLARE
    v_emprec        VARCHAR2(120);
    CURSOR emp_cur IS SELECT * FROM emp ORDER BY empno;
BEGIN
    FOR i IN emp_cur LOOP
        v_emprec := i.empno || ',' || i.ename || ',' || i.job || ',' ||
            NVL(LTRIM(TO_CHAR(i.mgr,'9999')),'') || ',' || i.hiredate ||
            ',' || i.sal || ',' ||
            NVL(LTRIM(TO_CHAR(i.comm,'9990.99')),'') || ',' || i.deptno;
        DBMS_OUTPUT.PUT_LINE(v_emprec);
    END LOOP;
END;

7369,SMITH,CLERK,7902,17-DEC-80 00:00:00,800.00,,20
7499,ALLEN,SALESMAN,7698,20-FEB-81 00:00:00,1600.00,300.00,30
7521,WARD,SALESMAN,7698,22-FEB-81 00:00:00,1250.00,500.00,30
7566,JONES,MANAGER,7839,02-APR-81 00:00:00,2975.00,,20
7654,MARTIN,SALESMAN,7698,28-SEP-81 00:00:00,1250.00,1400.00,30
7698,BLAKE,MANAGER,7839,01-MAY-81 00:00:00,2850.00,,30
7782,CLARK,MANAGER,7839,09-JUN-81 00:00:00,2450.00,,10
7788,SCOTT,ANALYST,7566,19-APR-87 00:00:00,3000.00,,20
7839,KING,PRESIDENT,,17-NOV-81 00:00:00,5000.00,,10
7844,TURNER,SALESMAN,7698,08-SEP-81 00:00:00,1500.00,0.00,30
7876,ADAMS,CLERK,7788,23-MAY-87 00:00:00,1100.00,,20
7900,JAMES,CLERK,7698,03-DEC-81 00:00:00,950.00,,30
7902,FORD,ANALYST,7566,03-DEC-81 00:00:00,3000.00,,20
7934,MILLER,CLERK,7782,23-JAN-82 00:00:00,1300.00,,10

7.4.9 SERVEROUTPUT

The SERVEROUTPUT procedure provides the capability to direct messages to standard output of the command line or to the message buffer. Setting SERVEROUTPUT(TRUE) also performs an implicit execution of ENABLE.

The default setting of SERVEROUTPUT is implementation dependent. For example, in Oracle SQL*Plus, SERVEROUTPUT(FALSE) is the default. In PSQL, SERVEROUTPUT(TRUE) is the default. Also note that in Oracle SQL*Plus, this setting is controlled using the SQL*Plus SET command, not by a stored procedure as implemented in Postgres Plus Advanced Server.

SERVEROUTPUT(stdout BOOLEAN)

Parameters

stdout

Set to TRUE if subsequent PUT, PUT_LINE, or NEW_LINE commands are to send text directly to standard output of the command line. Set to FALSE if text is to be sent to the message buffer.

Examples

The following anonymous block sends the first message to the command line and the second message to the message buffer.

BEGIN
    DBMS_OUTPUT.SERVEROUTPUT(TRUE);
    DBMS_OUTPUT.PUT_LINE('This message goes to the command line');
    DBMS_OUTPUT.SERVEROUTPUT(FALSE);
    DBMS_OUTPUT.PUT_LINE('This message goes to the message buffer');
END;

This message goes to the command line

If within the same session, the following anonymous block is executed, the message stored in the message buffer from the prior example is flushed and displayed on the command line as well as the new message.

BEGIN
    DBMS_OUTPUT.SERVEROUTPUT(TRUE);
    DBMS_OUTPUT.PUT_LINE('Flush messages from the buffer');
END;

This message goes to the message buffer
Flush messages from the buffer

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