How to change report query dynamically in Oracle APEX?

Question

Hi,
I want to dynamically change the where condition in APEX report query. Can anyone help me solve my this problem?
(Just want to change the query which we change in Oracle Reports using lexical parameter to change &Where, &Order by etc. dynamically!!)
Thanks, Praful

Answer 1

Hi
I've been using flexible queries in APEX for a few years now, and your question just added a whole new dimension to the flexible and powerful nature or writing reports in APEX.
While APEX Interactive reporting has almost completely removed the need the equivalent of Lexicals in Oracle Reports, I thought it might be fun to try and use lexicals in an APEX report.
Before we start I should summarise the powerful capability of APEX reporting to have oprtional parameters (lots and lots of them if this is needed).
For each parameter, you simply add a page item which will hold the value of the parameter.
The item/parameter can be populated by typing in the value, defining an LOV, using a date-picker etc.
To make the parameter optional simply use an OR in the where clause.
So for a apge item P200_PARAM1.....include
WHERE (:P200_PARAM1 IS NULL
OR COLUMN1 = :P200_PARAM1)
This way you can either leave the page item null or type in / select a value from a LOV.
There is a small quirk in APEX LOV's which sometimes returns a value of '%' or '%null%' - depending on the version - when no value is selected.
See Patrick Wolf's solution for this at Re: Null value handling in LOVs
I include this Application Process in all my APEX applications ;)
Now let's look at using the equivalent of Oracle Reports Lexicals......
First-off - this is based on the APEX SQL report - NOT Interactive Report.
It relies on the fact that you can let the query be parsed only at runtime.
1. Define an SQL report entering the 'core' of your query.
With a query like SELECT ENAME, JOB FROM EMP
Select 'Generic Columns' option in the 'Column Headings' section
Finish the report creation
2. Define a page item - say P200_LEXICAL - type text on the page
3. Edit the report and update the SQL query to include your lexical page item
SELECT ENAME, JOB FROM EMP &P200_LEXICAL. (REMEMBER THE '.' AT THE END)
Ensure that the option "Use Generic Column Names (parse query at runtime only)" is selected at the bottom of the query
4. Add a button to the page -using 'Create a button displayed among this region's items' the will submit the page.
5. Run the page - you will see all the employee names and job desdriptions
6. Enter a where clause into the 'Lexical' textbox - say "WHERE ENAME LIKE 'K%'" and click the 'Go' button
Voila! your where clause is magically applied.
Try any variant you like adding an ORDER BY clause etc...... this is FUN!
7. Clear the value of the LEXICAL and click go.
Edit the report and move the &P200_LEXICAL. into the selected columns (or add another one)
SELECT ENAME, JOB &P200_LEXICAL. FROM EMP
8. Run the page
Enter ",SAL" in the textbox and "Go"
We can add as many columns as we like (subject to the "Maximum number of generic report columns:" set below the SQL query in the report edit section)
Now because we have all the flexibility in APEX of setting page items using SQL or PLSQL you can set the value of the lexical programatically, or just pre-set a few values in an LOV - the options are limitless.
While I've never had the need to use lexicals - you can see that APEX provides the most Flexible Lexicals in town.
Eat your heart out "Oracle Reports"!!!
Have fun
Mike