Oracle Reports FAQ:
 I switched the page size to 11x8.5, but the printer still prints in portrait
Even though you set the page size in the report properties, there is a another variable in the system parameters section under the data model in the object navigator called orientation. This sets the printer orientation. Oracle starts by setting it to "default" which means that no matter how you set the page size, the user's default printer setup will be used. You can also set it to either "Landscape" or "Portrait" to force the printer orientation no matter what the user has set as default. These sorts of picky, minor details are the ones which are invariably forgotten when you are designing your report and are the reason I created our two report templates, reptmp_p and reptmp_l (portrait and landscape). For anyone who wants a consistent look in their reports I strongly recommend building a similar pair to save yourself an ulcer, unless you actually like starting from scratch every time!?!
 I've moved field into a repeating frame, but still get a "frequency below it's group" error
Moving fields around does not change what enclosing object is considered it's parent group. Oracle carefully remembers what repeating frame a field was originally placed in and assigns that as it's parent. If you then reference a column further down the line of the query structure it will return that error. If you are not exactly sure which repeating frame a field belongs to, try dragging it out of all of them. Whichever frame will not allow it to escape is it's parent. To change a field's parent, first click on the lock button on the speedbutton bar. It should now look like an unlocked padlock. Now all of the fields on the layout can be repositioned regardless of their original parent items. When you are satisfied with the repositioning click the lock button again to lock the layout. Oracle will parse the layout and assumes that any item fully enclosed in a repeating frame is a child object of that frame. This can be confirmed again by trying to drag an object out of it's parent. (Cntrl - Z or edit..undo will put it back where it came from)
Sometimes, for unknown and mysterious reasons, this method does not work. The alternative in this case is to highlight the field (or fields), cut it (cntrl-x), and then paste it into the desired frame. The paste does not initially set it into the right frame, but if you drag and drop it there before clicking on any other objects, and then click on something else, Oracle will usually figure what your intent was and assign the object(s) as a child of that frame. This is my preferred method of changing a field's parent as it works much more consistently then the unlock/lock method. One note though, if you are reassigning a group of fields, make sure the frame you are going to move them into is large enough to accept the whole group at once before you do the cut/paste. If you do the paste and then try to grow the frame to fit, you will have to cut and paste again. Once you de-select an object that has just been pasted, Oracle will assign it as a child of whatever it is in at the time.
If this technique also fails, you are probably going to have to delete and then recreate the objects within the desired frame. If the object has triggers attached, save yourself some typing by creating the new object in the right frame, copying over the trigger code, and then deleting the old object.
 Why does part of a row sometimes get shifted to the next page, but not all of it?
This is due to the way the scan works when Oracle is parsing the layout. If the tops of all the fields in a row are aligned and the fields are all of the same height and font, they should all stay together. I suspect, however, that Reports bases it's decision on the printed size rather than the field size you define to determine which objects are too large and must be shifted to the next page. This means that even if you set two fields top-aligned with the same height and font but one of them is bolded, the bolded field could get shifted to the next page due to it's bigger footprint. The solution is to put the whole row into a regular frame which is page protected.
 What does the "Print Condition" do?
The print condition type First, All, All but first, Last, All but last refer to the frequency with which you want to appear based upon the setting of the print condition object. A print condition object of Enclosing Object is whichever object encloses the current object (could be the parent or a frame within the parent), while Anchoring Object is the parent object (unless you have explicitly anchored the object in which case it is the object to which it is anchored). The key here is that this is about the pages on which the Print Condition Object appears, not the current object. Oracle views First as the first page on which any part of the Print Condition Object is printed, likewise Last is the last page on which any part of the Print Condition Object is printed. For objects inside a repeating frame, this condition is re-evaluated for each instance of the frame.
As an example, assume we have created a field inside a repeating frame with Print Condition Object set to 'anchoring object', and Print Condition Type set to 'All But First'. On every instance of that repeating frame which is printed entirely within a single page, our object will not print. However, if an instance of that frame spans more than one page then our object will print on the second and every subsequent page that this instance of the repeating frame spans.
For most objects you will not have to play with this print condition setting as the default setting is pretty good at determining what pages to print on, even though it only chooses between 'first' and 'last'. Only such things as heading objects you want reprinted on multiple pages are normally candidates for fooling around with this setting.
 Create dynamic 'where' which the user can input on the parameter form for my select statement
While setting a simple parameter for use in defining the select statement, such as a date, bill_period_id etc. is simple, there are times when you may wish to allow a user to add any "where" statement they wish. However, if you create a varchar user variable and try to reference it as an SQL condition ( e.g. Select * from account where :usercondition) you will get an error. The secret is that the variable must be initialized to a valid SQL condition before the Data Model will accept it. This is done in the "Initial Value" spot on the variables' properties form. The usual default is "1 = 1" which simply means all rows meeting whatever other conditions are included in the select statement will pass this condition if the user does not change it in the parameter form.
 How do I change a user parameter at runtime from a layout object trigger?
Quite simply, you can't. Once the BeforeReport trigger has fired, Reports locks down the user parameters until the report is finished. Oh, I know you can put a statement into a layout trigger at design time and the compiler will accept it, but the moment you run the report you will get a nasty error and the report will die. Why they couldn't catch those problems at compile time I have no idea, except that it probably uses the same PL/SQL compiler as Forms which uses that same syntax for the perfectly acceptable function of changing field values.
That being said, there is valid technique to mimic having a user variable which can be changed over the course of the report execution. What you have to do is create a PL/SQL package that contains a variable as well as the functions to read and write to that variable. Since variables inside a package are both local to that package and persistent over the duration of the run, you use this to save and change your variable value. I know that this seems like overkill, but it is the most efficient way of handling an issue that is very rarely encountered. As you can probably guess, this technique is a last resort to finding an SQL work around if one exists.
 How do I set the initial values of parameters for the parameter form at runtime?
This is what the BeforeForm trigger is primarily used for. Even if you have used a select statement to create a lookup list for the parameter, this statement is fully parsed before the parameter form is opened. Simply setting the parameter to a given value in the BeforeForm trigger will select that option as the default value displayed to the user. For example, assume you have a parameter called p_input_date which is intended to hold an invoice date. The following example will select the most recent invoice date as the default, and note that it properly handles exceptions to ensure that the report does not arbitrarily die if this default setting fails. Note also that like all report triggers, it must return a true or false value.
function BeforePForm return boolean is begin select max(bill_period_end_date + 1) into :p_input_date from billing_period where bill_period_end_date <= (select trunc(sysdate) from dual); return (TRUE); exception when others then :p_input_date := null; return true; end;
 Why can't I highlight fields and change all their format masks or print conditions at once?
You can. If you highlight a bunch of objects and then right click and select "properties..", Oracle gives you a stacked set of the individual properties forms for each of the selected objects. While this may be useful for some things, it requires changing values individually for each object. However, instead you can select the group of fields and then select "Common properties" from the "Tools" menu which will allow you to set the format mask , print conditions etc. for the whole set of objects at once.
 How do I change the printed value of a field at runtime?
Triggers are intended to simply provide a true or false return value to determine whether an object should be printed. It is generally not allowed to change any values held in the cursor, make changes to the database, or change the value of it's objects value. That being said, there is a highly unpublicized method of doing just that using the SRW.Set_Field_Char procedure. The syntax is SRW.Set_Field_char(0,<newstring>) and the output of the object that the current trigger is attached to will be replaced by <newstring>. There are also SRW.set_fileld_num, and SRW.set_field_date for numeric or date fields.
While these options do work, they should only be used if a suitable NVL or DECODE statement in the original query is not possible as they are much, much slower to run. Also, note that this change of value only applies to the formatted output. It does not change the value held in the cursor and so can not be used for evaluating summary totals.