I demonstrated a number of SQL approaches to reading object types in Appendix B of the Oracle Database 12c PL/SQL Programming book. For example, the easiest one to construct and return the results from a
TO_STRING member function uses the
SELECT TREAT(base_t() AS base_t).to_string() AS "Text"
However, it seems that I could have provided one more. Here’s an example of how you can (more...)
If you’re not using Toad DBA Suite, it’s sometimes hard to find solutions. Somebody wanted to know how to find indexes that aren’t that aren’t indirect. Indirect indexes are those created for a primary key because a primary key column or set of columns are both not null and uniquely constrained. You can’t drop a unique index for a primary key without dropping the primary key constraint that indirectly created it.
The following query (more...)
It seems impossible to raise an exception when handling no_data_needed.
create or replace function demo return sys.odciNumberList pipelined
exception when others then
dbms_output.put_line('in exception handler, sqlcode: ' || sqlcode);
email@example.com > select * from table(demo());
ORA-06501: PL/SQL: program error
ORA-06512: at "SOKRATES.DEMO", line 8
ORA-01476: divisor is equal to zero
no rows selected
in exception handler, sqlcode: -1476
Do you write PL/SQL? Me too!
Trouble is, sometimes it's hard to decide how to structure your packages - particularly in an APEX project. Over at the PL/SQL Challenge
website run by Steven Feuerstein and friends there is a page dedicated to roundtable discussions.
I submitted my question not so long ago and hope to get some interesting responses. Why don't you give the site a visit and contribute? The discussions usually last for about (more...)
Disclaimer: I’m not posting to make me look better, we’ve all written code that we’re later ashamed of, and I’m no different!
This is some code from a system I was maintaining some time ago. I’ve kept it since then because it illustrates a number of things NOT to do:
(in_password IN VARCHAR2)
-- do NOT copy this code!!! ...
RETURN VARCHAR2 IS
CURSOR cur_rules IS
If you want to be able to create contemporary high-performing PL/SQL code, welcome to my training event in NYC (hosted by NYOUG) on November 7, 2014:
I think, it is as important as ever to follow best practices for server-side development. There are lots of options that could get the job done "now", but very few that would survive for months/years. Also, there is a constant pressure from various "alternative" solutions to (more...)
My session on "Oracle 12c for Developers" is done.Afterwards someone asks the question:
What happens when you use DBMS_REDACT with a complete row update?
My guess was that it would place the redacted data in the column, but I haven't tried it, so here goes:
create table emp
,to_char (abs (dbms_random.random)) credit_card
(object_schema => 'A'
,object_name => 'EMP'
,policy_name => 'Hide Creditcard'
It seems to me that I talked about my most recent book everywhere except for my own blog... So, let me introduce you a one and only performance tuning book dedicated to PL/SQL
This book took me much longer to write than I initially anticipated - and to be fair, that's the reason for staying quiet at the blog. I just didn't have time/energy to write everywhere :-) Although, it was fun writing - (more...)
The EOUC (EMEA Oracle User Group Community) hosts a special session on sunday during Oracle Open World. This session contains twelve things about Oracle 12c. Each of these 12 things is hosted by a different speaker, so this means that each section is only five minutes long (Strictly guarded by Debra Lilley).
Thankfully I was chosen to be one of the speaker during this special session, very excited and also very scared. (more...)
While preparing for my session at Oracle Open World on "Oracle 12c for Developers" I ran into a little remarkable thing.
When sorting a dataset, the sorting is always done last. That is what I was taught anyway. There is probably some obscure way to detect the exact execution plan, but personally I never bothered to go and investigate.
When I was created some test scripts I found there was a way to see that (more...)
A comparison of sucking data into a table over a db link using DBMS_PARALLEL_EXECUTE.
This particular example is based on something I needed to do in the real world, copying data from one database into another over a db link. Datapump is not available to me. Tables in question happen to be partitioned by a date-like number (boo!) hence some of the specific actions in the detail.
I think it’s a good example of (more...)
Sorry for staying quiet for some time, but for some good reasons. Some of these reasons will be explained in later posts, but for now I would like to share the story I wrote upon request of Steven Feuerstein
, who asked to tell how PL/SQL impacted our life. Here is my story:
I started to work with databases already in college, but more from the data modelling/business analysis angle. When I moved to (more...)
A recent addition to my Oracle PL/SQL library is the book Oracle PL/SQL Performance Tuning Tips & Techniques by Michael Rosenblum and Dr. Paul Dorsey.
I agree with Steven Feuerstein’s review that “if you write PL/SQL or are responsible for tuning the PL/SQL code written by someone else, this book will give you a broader, deeper set of tools with which to achieve PL/SQL success”.
In the foreword of the book, Bryn Llewellyn writes:
The UTL_FILE database package is used to read from and write to operating system directories and files. By default, PUBLIC is granted execute permission on UTL_FILE. Therefore, any database account may read from and write to files in the directories specified in the UTL_FILE_DIR database initialization parameter [...] Security considerations with UTL_FILE can be mitigated by removing all directories from UTL_FILE_DIR and using the Directory functionality instead.
© Eddie Awad's Blog, (more...)
I was aware that up to Oracle 11g, a PL/SQL program wasn’t allowed use an associative array in a SQL statement. This is what happens when I try to do it.
SQL> drop table test_array purge;
SQL> create table test_array as
2 select level num_col from dual
3 connect by level <= 10;
SQL> select * from test_array;
Steven Feuerstein was dismayed when he found in a PL/SQL procedure a cursor FOR loop that contained an INSERT and an UPDATE statements.
That is a classic anti-pattern, a general pattern of coding that should be avoided. It should be avoided because the inserts and updates are changing the tables on a row-by-row basis, which maximizes the number of context switches (between SQL and PL/SQL) and consequently greatly slows the performance of the code. Fortunately, (more...)
Yesterday the Anti-Kyte (a.k.a. Mike) published a great post on coding styles
. I started to post a comment but ended up rambling to I thought I'd put my thoughts here.
I can't be one to comment on tangential intros (just look at any of my presentations), but he almost lost me when I thought the entire post was going to be soccer jokes I didn't get but switched in time to three controversial (more...)
In my previous blog post I gave some PL/SQL that performed the tokenising of a string. Check out this blog post here.
Thanks also to the people who sent me links examples of how to tokenise a string using the MODEL clause. Yes there are lots of examples of this out there on the interest.
While performing the various searches on the internet I did come across some examples of using Regular Expressions to extract (more...)
Over the past while I've been working a lot with text strings. Some of these have been short in length like tweets from Twitter, or longer pieces of text like product reviews. Plus others of various lengths.
In all these scenarios I have to break up the data into individual works or Tokens.
The examples given below illustrate how you can take a string and break it into its individual tokens. In addition to tokenising (more...)
In my previous blog post
, I took a look at the new APEX_JSON package that ships with Apex 5.0 and its capabilities for parsing JSON.
In this blog post, I am going to look at how the APEX_JSON package can be used to generate JSON from data in your database using PL/SQL.
There are multiple ways of creating JSON output using the APEX_JSON package. There are several overloaded write() procedures which can output (more...)