Editing Data in the Meta Data Base: OracleForm "updateMDB"

General Remarks

Under Construction

As many other programmes, the updateMDB OracleForm seems to be continously "under construction". However, as a first approach to an update tool for CERA meta data it seems to work, although nobody can guarantee that it is free of bugs.
So there is still further development to be done. Especially, the handling of changes of SPATIAL_ and TEMPORAL_COVERAGE are not very intuitive.

Risks

Unlike the OracleForm loadMDB the updateMDB form has direct access to the CERA data tables. The changes are committed to the database as soon as they are saved. There is no intermediate layer for any kind of check, whether or not the changes are of any value. For this reason it is strongly recommended, that only such operators (:=users) should use the form that are aquainted to the CERA system and its philosophy. This is especially valid for changes of records of the 2nd level entities (see below).

Usage of the Form

Although updateMDB allows to edit nearly all fields in the CERA-2 database, not all fields on all canvases are editable. On some canvases there are display fields in addition to the editable ones. In these cases the contents of the display fields can be updated on another canvas, usually reachable by a button. All display data is written in black, while changeable data is written in blue.
Whereever possible entries in a field should be changed by using the list of values (LOV). It can be called by pressing Ctrl+L. Whether or not an LOV is available for a certain field can be seen from its title: it is blue for fields with LOV, black otherwise. Entries that are not equal to a value of the LOV are rejected.

The Structure of the Canvases

The OracleForm "updateMDB" consists of four types of canvases: The main canvas, the LOV canvases, the 1st level sub-canvases and the 2nd level sub-canvases.

The Main Canvas (white)

The Main canvas is not for any editing or updating. It is just for submitting the query for the ENTRY(s), that are to be changed.
In the upper part of the main canvas you can enter your query.
In the central part of the main canvas are blue buttons that lead you to the 1st level canvases, where you can change all information of the CERA relational tables. So many of the buttons refer to CERA Blocks.
In the lower part of the main canvas are yellow buttons that lead you to the LOV canvases. Press the appropriate one, if you want to change one of the pull down menues.
Observe the lowest line on the main canvas (console). It is the output of all system messages during your session. Error messages at the moment of saving often get clearer when you use the "Display error"-information under the "Help" menue.

The LOV Canvases (more or less yellow)

The LOVs should contain well defined objects/keywords, which may differ from institute to institute according to the local needs. If you do not find the right word in an LOV pull down menu, you can edit the menu list by pressing one of the yellowish buttons at the bottom of the main canvas. A new canvas of the same colour will open and you can enter a new object/keyword by pressing the green "insert new value ..." button (the button only retrieves the next free sequence value for the _id; if you know a free _id number you can use the Oracle Record-Insert menue point as well).
If you edit on an LOV canvas an existing entry of the pull down menue, these changes are done for all CERA ENTRYs that refer to it.

The 1st Level Sub-Canvases (more or less blue)

Most information belonging to a CERA ENTRY is changed on the blue 1st level sub-canvases, available by pressing the appropriate blue button on the main canvas.
Mind the differences (blue/black) of data fonds and title fonds as explained above ("Usage of the Form")!

The 2nd Level Sub-Canvases (more or less red)

You can edit the five entities on the second level (SUMMARY, QUALITY, SPATIAL_COVERAGE, TEMPORAL_COVERAGE, and DATA_ACCESS) by pressing the reddish button on a 1st level canvas. When you work on the appearing reddish canvas, special care has to be taken:
Several ENTRYs in CERA may refer to the same record of these 2nd level tables. Whether this is the case you see in the upper part of the canvas: a list is shown there, of all ENTRYs that refer to the same record. If only one ENTRY is displayed, no special care has to be taken. However, there may be a long list of ENTRYs, all refering to the same record.
In this case, e.g., an update of a QUALITY record will change the quality information of all ENTRYs that refer to it. This may make sense, if you correct a misspelling or if all the ENTRYs are related. However, if the quality information is, e.g. the words "not filled" you probably want to edit the data of one certain ENTRY only. You normally do not want to set all ENTRYs with a missing quality information to the same new value. In those cases a new record has to be created in the second level entity, being referred to by only one ENTRY. So:

If you are on one of the red 2nd level sub-canvases and you want to edit the record itself and to change this data for all ENTRYs referring to it, you just enter the changes as usual in the lower part of the form.
This is also valid, if only one ENTRY refers to the record in the sub-canvas, i.e. only one entry is displayed in the upper part of the form.
If various ENTRYs refer to the record to be changed and you want to edit the record only for the selected ENTRY (=the current record on the main canvas) press the green "new record" button and edit the new record that appears (which will be defaulted to the old one).

If you return from a 2nd to a 1st level canvas, your changes will not yet be displayed. You will not see them before they are saved and a new query on the main canvas is done.
There is a difference between the SUMMARY, QUALITY, and DATA_ACCESS canvases on one hand and the _COVERAGE (SPATIAL_ and TEMPORAL_) canvases on the other:
For the first you simply do your changes and return to the 1st level canvas. So you cannot refer with your ENTRY to an existing SUMMARY, QUALITY or DATA_ACCESS record.
For the _COVERAGEs you can do your changes in the same way, but you also can link your ENTRY to an existing TEMPORAL_ or SPATIAL_COVERAGE record. To do this, you can select the approriate record from the pull down menue on the first level canvas. So here you can do changes without calling the second level canvas, if in _COVERAGE already a record exists, that fits your needs.

Error Reports

As the Forms are not yet readily debugged, you well may encounter errors. If an error occurs you should:

look at the foot line on the main canvas,
find the corrupt SQL statement in the "Help"-menu ("Display error"),
find the interpretation of Oracle error codes like FRM-24459 in the Oracle Handbook and/or by typing "oerr frm 24459" on Unix level,
report errors to Frank Toussaint if applicable.

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Last change: Fri May 28 21:36:20 NFT 1999