Duncan Mein's Blog

Recently our test department raised a bug against one our applications that occurred when trying to insert a record into a table. The error message encountered was a fairly innocuous " ORA-01704: string literal too long ". Following the test case to the letter, I successfully generated the same error and located the table that the APEX form was inserting into. A quick check of the Data Dictionary confirmed that the column in question was of type VARCHAR2(10). At this stage, I though the obvious cause was that there was no limit on the APEX form item (a Text Area) of 10 characters. Having checked the item in question, not only was there a “ maxWidth ” value of 10, the text area had been created with a “ Character Counter ”. Strange then how a form item accepting 10 characters was erroring whilst inserting into a column of VARCHAR2(10). A little while later...... (after some head scratching and several discussions with our DBA’s and a colleague) the problem was all too clear. S

The following query is a very simple way of identifying all report columns within your APEX application that may be exposed by Cross Site Scripting (XSS). XSS allows an attacker to inject web script (JavaScript) into an application and when this is rendered in the report, the script is interpreted rather than rendered as text. To safe guard against this attack, APEX provides a "Display as Text (escape special characters)" report column attribute that can be applied to classic and Interactive Reports. This causes the script text to be displayed as text rather than interpreted by the browser. If you have any markup (HTML) within your query that the report is based on, this markup will also be displayed as text and not interpreted. I personally think this is a good by product as you should not really be coding look and feel into your raw SQL. Anyway I digress. Here is the query that will identify all vulnerable report columns within your APEX application: SELECT application_id

I have been using Oracle SQL Developer Data Modeller for a while now within a Windows XP environment. It seems pretty good (albeit a little slow but hey show some an Oracle Java client application that is quick. Oracle Directory Manager?, OWB Design Centre? I shall labour this point no more) and I was looking forward to trying it out on my new 27" iMac. I promptley downloaded the software from OTN and a quick read of the instructions suggested I need to do no more other than run the datamodeler.sh shell script since I already had Java SE 6 installed. As it turns out, the datamodeler.sh script in the root location does little more than call another script called datamodeler.sh found in the /datamodeler/bin directory which is the once you actually need to execute to fire up SQL Data Modeler When this script runs, it prompts you for a the full J2SE file path (which I had no idea where it was) before it will run. After a quick look around google and I came across the command: java_ho

This cool example is not one I can take the credit for but since it is used pretty heavily in our organisation, I thought I would share it as it's not only pretty cool buy also demonstrates how useful Oracle Pipelined functions can be. In essence a Pipeline table function (introduced in 9i) allow you use a PL/SQL function as the source of a query rather than a physical table. This is really useful in our case to generate all the days in a calendar month via PL/SQL and query them back within our application. To see this in operation, simply create the following objects: CREATE OR REPLACE TYPE TABLE_OF_DATES IS TABLE OF DATE; CREATE OR REPLACE FUNCTION GET_DAYS_IN_MONTH ( pv_start_date_i IN DATE ) RETURN TABLE_OF_DATES PIPELINED IS lv_working_date DATE; lv_days_in_month NUMBER; lv_cnt NUMBER; BEGIN lv_working_date := TO_DATE(TO_CHAR(pv_start_date_i, 'RRRRMM') || '01', 'RRRRMMDD'); lv_days_in_month := TRUNC(LAST_DAY(lv_working_date)) - TRUNC(lv_work

Server virtualisation is something I have been using for a few years now both at work and at home. I mainly use VMWare Fusion on my MacBook Pro and VMWare Workstation / Player on an old Windows Laptop. For everyday tasks these products are amazing as i can run an XP VM on my MacBook Pro for all those times I need to open MS Project or run TOAD. On my server at home, I didn't want to install a host OS and then install VMWare Workstation / Server to host several Linux VM's. Instead I explored the option of a "Bare Metal" hypervisor from VMWare (ESXi 3.5 Update 3). A hypervisor is a very small linux kernel that runs natively against your servers hardware without the burden of having to install a host OS. From here you can create and manage all your VM's remotely using the VMWare Client tool. For more information in ESXi, check out VMWare's website here Reading the documentation suggested that ESXi was very particular about the hardware it supports and so began th

In one of our Applicaitons, the table DEPT contains a self referncing join (Pigs Ear) as it models our organsational department hierarchy. For example: CREATE TABLE DEPT ( DEPT_ID NUMBER NOT NULL ,PARENT_ID NUMBER ,DEPT_NAME VARCHAR2 (100) NOT NULL ,EMPLOYEES NUMBER NOT NULL ,CONSTRAINT DEPT_PK PRIMARY KEY (DEPT_ID) ,CONSTRAINT DEPT_FK01 FOREIGN KEY (PARENT_ID) REFERENCES DEPT (DEPT_ID) ); INSERT INTO DEPT VALUES (1,NULL,'IT', 100); INSERT INTO DEPT VALUES (2,1,'DEVELOPMENT', 12); INSERT INTO DEPT VALUES (3,1,'SUPPORT', 15); INSERT INTO DEPT VALUES (4,1,'TEST', 25); INSERT INTO DEPT VALUES (5,2,'PL/SQL', 2); INSERT INTO DEPT VALUES (6,2,'Java', 1); INSERT INTO DEPT VALUES (7,2,'SQL', 11); INSERT INTO DEPT VALUES (8,2,'C++', 3); INSERT INTO DEPT VALUES (9,4,'Functional', 3); INSERT INTO DEPT VALUES (10,4,'Non Functional', 5); COMMIT; A quick tree walk using CONNECT BY PRIOR shows you the Parent / Child rel

There is a really cool JavaScript function in Apex called: $f_CheckFirstColumn that allows you to Check / Uncheck all checkboxes that exist in the 1st column position of a Tabular Form / Report. To implement this, all you need do is add the following HTML to the Column Heading of the 1st Column in your Tabular Form (i.e. the Checkbox Column): <input type="Checkbox" onclick="$f_CheckFirstColumn(this)"> Check out an example here