Pretty print in Oracle PL/SQL - oracle

Question

Is there a better way to print to STDOUT in Oracle PL/SQL?
DBMS_OUTPUT.PUT_LINE seems very basic and coarse.
Should there be something like Python's pprint (Pretty Print)?

Answer 1

PL/SQL is designed to process data, not display it, or interact with the client calling it (so there's no mechanism for user input, for example).
The DBMS_OUTPUT package "enables you to send messages from stored procedures and packages. The package is especially useful for displaying PL/SQL debugging information". It isn't designed for 'pretty' output because PL/SQL isn't designed for that kind of work. And it's important to realise that the client calling your procedure might not look at or display the DBMS_OUTPUT buffer, so what you write to it could be lost anyway.
PL/SQL doesn't print anything to stdout; the DBMS_OUTPUT calls write to a buffer - if it's enabled at all - and then once the PL/SQL has finished executing, the client can read that buffer and display the contents somewhere (again if it's enabled). That also means you can't use it to track progress, since you don't see anything during execution, only when it's complete; so even for debugging it's not always the best tool.
Depending on what you're trying to do you can make things look slightly better in SQL*Plus by having doing set serveroutput on format wrapped, which stops it losing whitespace at the start of buffer lines. But that's usually a minor benefit.
More generally your procedure should pass the results of its processing to the caller via OUT parameters, or by making it a function that returns something useful.
If you're currently trying to display the results of a query using dbms_output.put_line then that isn't a good idea. You could instead return a collection or a ref cursor to the client, and allow the client to worry about how to display it. You can easily display a ref cursor in SQL*Plus or SQL Developer using bind variables.

Answer 2

Pretty enough?
--Pretty print
CREATE OR REPLACE PROCEDURE PP(input varchar2, p_pn varchar2:='PP')
AS
pos INTEGER;
len INTEGER := 4000;
nl VARCHAR2 (2) := CHR (10);
r_ VARCHAR2 (2) := CHR (13);
v_padded varchar2(64):=p_pn;--rpad(p_pn, 5, ' ');
BEGIN
IF LENGTH (input) > len
THEN
pos := INSTR (input, nl, 1, 1);
IF pos > 0 AND pos < len
THEN
DBMS_OUTPUT.put_line (v_padded||': '||REPLACE (SUBSTR (input, 1, pos - 1), r_, ''));
pp (SUBSTR (input, pos + 1),p_pn);
ELSE
IF pos = 0 AND LENGTH (input) <= len
THEN
DBMS_OUTPUT.put_line (v_padded||': '||REPLACE (SUBSTR (input, 1, len), r_, ''));
ELSE
DBMS_OUTPUT.put_line (v_padded||': '||REPLACE (SUBSTR (input, 1, len), r_, ''));
pp (SUBSTR (input, len + 1),p_pn);
END IF;
END IF;
ELSE
DBMS_OUTPUT.put_line (v_padded||': '||REPLACE (SUBSTR (input, 1, len), r_, ''));
END IF;
EXCEPTION
WHEN OTHERS
THEN
RAISE;
END PP;
Sample output:
SQL>
FUN_ENCRYPT_PERSON_ID: Input = 123456789123
FUN_ENCRYPT_PERSON_ID: Suffix = 123
FUN_ENCRYPT_PERSON_ID: Base = 876543210
FUN_ENCRYPT_PERSON_ID: 2->5 1 10000 10000
FUN_ENCRYPT_PERSON_ID: 3->9 2 200000000 200010000
FUN_ENCRYPT_PERSON_ID: 4->2 3 30 200010030
FUN_ENCRYPT_PERSON_ID: 5->1 4 4 200010034
FUN_ENCRYPT_PERSON_ID: 6->3 5 500 200010534
FUN_ENCRYPT_PERSON_ID: 7->6 6 600000 200610534
FUN_ENCRYPT_PERSON_ID: 8->4 7 7000 200617534
FUN_ENCRYPT_PERSON_ID: 9->8 8 80000000 280617534
FUN_ENCRYPT_PERSON_ID: Output = 280617534123

Answer 3

There is not a builtin that I'm aware of. But I wrote a proc to pretty-print a resultset from within a stored procedure.
The proc is called print_out_resultset. Example usage:
....
cursor mycur (mynum in number) is
select * from mytable where mycol >= mynum;
myrow mytable%rowtype;
myvar number;
...
begin
....
print_out_resultset(query_string =>
'select * from mytable where mycol >= :b1',
col1 => 'SAM', col2 => 'FRED', col3 => 'ERIC',
b1 => myvar,
maxrows => 4);
open mycur(myvar);
fetch mycur into myrow;
while mycur%found loop
....
example result
SQL> set serverout on;
SQL> execute myproc;
SAM FRED ERIC
-----------------------------------
32A 49B 15C
34A 11B 99C
11F 99A 887
77E 88J 976
the code is here: http://toolkit.rdbms-insight.com/print_out_resultset.php
I used this only for troubleshooting, many years ago; test before deploying in production of course

Answer 4

Actually there is a standard approach, but it works well only with varchar variables:
declare
v_str varchar2(100):= 'formatted';
v_int int := 10 ;
begin
dbms_output.put_line(
UTL_LMS.FORMAT_MESSAGE('Somebody told that "%s" output works well with '
||'varchar variables, but not with int variables: "%d". '
||'Only with constant integers (%d) it works.'
, v_str, v_int, 100)
);
end;

Answer 5

If you are trying to print json object, there is a better way to print using the JSON_UTIL_PKG and JSON_PRINTER.
L_JSON_LIST JSON_LIST;
L_JSON JSON;
L_CLOB CLOB;
BEGIN
--JSON_UTIL_PKG.SQL_TO_JSON returns a list, so storing it in a JSON_LIST.
L_JSON_LIST := JSON_UTIL_PKG.SQL_TO_JSON('SELECT
''abc'' "Address1",
''def'' "Address2",
''gh'' "City"
FROM
DUAL');
DBMS_LOB.CREATETEMPORARY(L_CLOB, TRUE);
--get the first item in the list
L_JSON := JSON(L_JSON_LIST.GET(1));
--It takes a json object and will return it in a clob.
JSON_PRINTER.PRETTY_PRINT(OBJ => L_JSON, BUF => L_CLOB);
--output
DBMS_OUTPUT.PUT_LINE(L_CLOB);
END;
And, the output looks like the following,
{
"Address1" : "abc"
,
"Address2" : "def"
,
"City" : "gh"
}

Answer 6

Maybe you are looking for fnd_file function
fnd_file.put_line(fnd_file.output,:message);
where :message is the value u want to print.