Acorn RISC PD-CD 1

home *** CD-ROM | disk | FTP | other *** search

/ Acorn RISC PD-CD 1 / Acorn RISC PD-CD 1.iso / utilities / powerbase / pbasedoc / _qtutorial next >

Wrap

Text File | 1994-02-01 | 14.9 KB | 293 lines

Quick Tutorial ============== This document is intended to acquaint the new user as painlessly as possible with the most commonly-used facilities of Powerbase. It does not explain how to create a database from scratch (the file 'Create' does that), nor does it delve into the many advanced features, but it does explain how to:- (a) Start up Powerbase and open an existing database. (b) Browse through the database and search for individual records. (d) Add new records and alter or delete existing ones. (d) Query the database to create simple reports. (e) Close the database. The supplied sample database 'Friends' is used to illustrate most of these activities. If you have a hard disc you should copy 'Friends' and Powerbase itself onto it before proceeding further. It is possible to use Powerbase from floppy discs only but some operations, such as creating reports, will be quite slow. Unless memory is very tight therefore, users of floppy discs are recommended to allocate at least 32K to the RAM disc and copy 'Friends' onto it. Everything will then run much faster. Powerbase can provide context-sensitive help via Acorn's !Help application and you are advised to load this, resizing the help window and placing it at the top right of the screen. Further help can be had by choosing the Help entry on Powerbase's main menu or on the icon-bar menu. Starting Powerbase ================== Double-click on the Powerbase icon. After a few seconds it will appear on the icon-bar with the words "No data" beneath it to show that no database is open. Dragging the 'Friends' icon onto the Powerbase icon on the icon-bar will open 'Friends' for use and the words "No data" will be replaced by the name of the database. Double-clicking on the 'Friends' icon has the same effect, in fact if Powerbase isn't already on the icon-bar a double-click on 'Friends' will install it for you provided that the Powerbase icon has been seen by the filer. Two windows will open. One is the RECORD WINDOW and displays the first record in the database - the one for "Badgery Peter". The other is the KEYPAD which allows you to control the browsing, searching and editing functions of Powerbase. The keypad is rather large and obscures quite a big area of the record window. The most-used buttons, however, are on the top two rows and the keypad can be moved part way off screen to get it out of the way. Browsing through the Records ============================ The top row of buttons on the keypad allows you to browse through the file. If you have !Help running, as previously suggested, it will tell you what each button does. Once you get the general idea you will find the symbols on the buttons logical and self-explanatory. The most commonly used ones act as follows: (a) The arrows at the ends of the row take you to the first and last records. You are looking at the first record now, so click (with SELECT) on the top-right button and you will see the record for Turnip Charles. The leftmost button takes you back to the start again. (b) Movement through the file one record at a time is achieved using the single arrow keys next door to the ones you have just used. Try them out, noting the way records come up in alphabetical, or reverse alphabetical, order. (c) The keys with double arrows allow you to make longer jumps through the file. The number of records skipped is shown in the writable icon between them and has a default value of 10. Since there are only 10 records in 'Friends' these keys will have the same effect as the "first" and "last" keys, unless you change the interval to something less. Click in the icon, delete the 10 and enter 5 or 2, then try the double-arrow keys again. Searching for a record ====================== The rightmost button on the third row of the keypad shows a question mark followed by a "record card" icon We will call it the Search button. When clicked with SELECT the keypad window grows an extension on the right-hand side. This new area contains a writable icon in which to enter the key of the record you wish to display. Suppose you want to see the record for "Bloggs Fred". You need to enter the KEY for the record. In this database keys are made up from the first 4 letters of the surname plus the initial. The required key is therefore BLOGF. Enter this and either click on OK or type <Return> and the record will be displayed. Note that the key is shown in the window heading. Editing the Database ==================== This part of the tutorial involves changes to the data records. Make a working copy of the disc and put the original in a safe place. If you are using a copy of 'Friends' on the RAM disc then the floppy disc won't be altered, but it's still not a good idea to work with the original disc. Modifying records ----------------- Pointing the mouse at any field and clicking SELECT places the caret in that field. The contents of the field may then be edited in the standard way for RISC OS writable icons. i.e. CTRL U clears the field. DELETE removes the character to the left of the caret. COPY removes the character to the right of the caret. SHIFT/COPY deletes the word to the right of the caret. CTRL/COPY deletes everything from the caret to the end of the line. ⇦ and ⇨ move the caret left/right by one character. SHIFT ⇦ and SHIFT ⇨ move the caret left/right by one word. CRTL ⇦ and CTRL ⇨ move the caret to start and end of the field. Changes made to a record cause the record to be written back to the database whenever you display a different record or close the database. (There is a button on the keypad called 'Force update' but you don't normally need to use it.) Recovering data after a mistake ------------------------------- You will sometimes edit the wrong field by mistake and want to restore the previous contents. Click MENU over the field. The second entry on the main menu contains the "tag" of the field. Follow the right-pointing arrow to the 'Field' sub-menu and choose the last entry: 'Undo changes'. Similarly, if you make a mess of a complete record and want to go back to the way it was you can choose 'Undo changes' from the main menu. It is important to realise that these 'undo' facilities will not work if you have looked at another record before using them (or clicked on 'Force update'). In other words you can recover data which has been altered in or removed from the currently-displayed record only. Adding and deleting records --------------------------- To add a new record you use the "add record" button which looks like a plus sign and an index card. Clicking on this offers a blank record into which you can type some new data. You don't have to complete all the fields, in fact the only field into which you MUST type something is the NAME field. This is the KEY FIELD; the one from which the key, mentioned earlier, is derived. If you leave the key field blank then nothing will be written to the database. Type the name "Bodmin George", then go to the beginning of the file and step through it record by record. You will find that your new record has been inserted in the correct place, i.e. the sequence goes: Badgery, Bloggs, Bodmin, Cavendish. Now let's try deleting the record you've just added. There is a "dustbin" button which will do just that: but don't use it yet. Make sure that the unwanted record is on the screen and click the button to the RIGHT of the bin. You will now find that the record has vanished; the names run straight from Bloggs to Cavendish, just as they did before you added Bodmin. Wasn't that rather TOO easy? Suppose you clicked the button by mistake and deleted an important record! Powerbase handles this very nicely. The record hasn't really been deleted at all. To prove this, click the button above the one you used for "deleting". The button shows a green right-pointing arrow and a "card index" icon. There's Bodmin again! You will soon find that it appears to be the ONLY record in the file! Don't worry; nothing has been lost. A Powerbase database is treated as six separate SUBFILES numbered 0-5. When you first open the database you are looking at Subfile 0 and the heading of the record window shows this. If you look at the heading now you will see that it has changed to Subfile 1. The buttons on either side of the bin carry pictures which suggest their true functions. They do NOT delete records; they merely MOVE records from one subfile to another. The right button moves the displayed record to the next subfile in sequence. Thus, in the above case the "Bodmin" record has been moved from subfile 0 to subfile 1. A record in subfile 1 would be moved to subfile 2 and so on. What happens when it gets to 5? The next click shoves it into subfile 0 where it was originally. As you might have guessed, the left button moves records in the opposite direction, i.e. from subfile 1 to 0 or from subfile 0 to 5. What happens when you DO want to lose a record for good? That's when you consign it to the dustbin! Since this button's action is more drastic than that of the other two you are asked for confirmation before deletion occurs. Printing Lists ============== Before Powerbase can produce a list it must be told: * which FIELDS should appear on the list * which RECORDS should appear on the list. Making the field selection -------------------------- Specifying the fields you want is extremely easy. To include a field simply point the mouse at it and click with ADJUST. The selected field will then appear in inverse video (i.e. normally white on black). If you change your mind about a field you can de-select it by clicking on it again with ADJUST. The order in which the fields will appear in the printed list is the order in which you select them. Take care with this since there is nothing on the screen to indicate what order the fields will be in. The fields chosen for inclusion in a printout make up a SELECTION which may be saved and reloaded for future use. Just for now select the name and the first 3 fields of the address. Choosing which records to print ------------------------------- Specifying which records to print is somewhat more complex, although efforts have been made to render it as simple as possible. With the mouse pointer in the record window click MENU. This displays the main Powerbase menu from which you should choose Print. A small window appears in which you can specify the criteria which must be met by records for inclusion in the list. If you just click OK (or type <Return>) without entering anything here you will obtain a list of the whole database (or, more accurately, of the the whole of the current subfile). Try this first. When the search is complete the list will be displayed in a window. If you point to a record in the displayed list and double-click with SELECT Powerbase will display the chosen record in the main record window. Note that the caret is placed in the field you were pointing to on the list. This is very useful if you spot errors in the data whilst examining a list. A double click on the offending item offers the record with the caret correctly positioned for editing. Most database queries, however, don't involve printing all the records! You will usually need to enter a SEARCH FORMULA before clicking OK. Search formulae can be quite complex and a more detailed treatment is given in another document. Only a few simple examples will be shown here. Enter the following and click OK: ADD2=Exeter The report window appears showing just one record: the one for Bloggs. ADD2 is called the TAG of the field. The label which appears beside a field on the screen is called its DESCRIPTOR and you might have expected such labels to be used to refer to fields in search formulae. This is not done for two reasons: (1) Descriptors can be inconveniently long for use in this way. (2) Fields don't necessarily have descriptors. Of the 5 address fields only the first has a descriptor (ADDRESS). Since every data field needs a "handle" of some sort we give each a tag, which is never more than 4 characters. Clicking MENU over a field makes its tag appear in the second menu item. You may have noticed that Bloggs' is not the only address in Exeter. There is another one but with Exeter in ADDR3 rather than ADDR2. Can we print both on the same list? Yes we can! The formula needed is: ADD2,ADD3=Exeter Notice the way the alternative tags are separated by commas. We call this a TAG LIST. A record will be printed if ANY of the tags in the tag list are matched. The part of the search formula after the = sign is the TARGET and here too we may specify several of them in a TARGET LIST. Try the following: ADD3=Exeter,Anytown and also: ADD2,ADD3=Exeter,Anytown The characters we want to match don't, of course, always make up the entire field. Can we search for PART of a field. Yes indeed! Suppose you wanted the records for people called Peter, Fred and Jean. Enter the formula: NAME{Peter,Fred,Jean and you will find that the records for Peter Badgery, Fred Bloggs and Jean Ford are printed. The { (left curly bracket) means "contains". i.e. the name field doesn't have to CONSIST of Peter, or Fred or Jean, but has to CONTAIN one of these names somewhere within it. Hard copy --------- So far you have only displayed reports in a window. What if you want to send them to your printer? Nothing could be easier. Load up !Printers, switch on the printer then click MENU over the displayed report. 'Save as text' leads to a standard 'Save' box from which you can drag the file icon to !Printers. You could, of course, also drag it to a directory window to save it. Or you could simply type <Return>, in which case the report would be saved with the default name 'List' in a directory called 'PrintJobs' which is inside the 'Friends' database directory. Every Powerbase database has a 'PrintJobs' directory to use as a general "dumping ground" for generated output. Such directories are apt to get cluttered and need "mucking out" from time to time. Closing down ============ A database may be closed down by choosing the Close database entry from the icon bar menu. When you do so all relevant data stored in memory is saved to disc and the database is closed. You do not have to do anything to save the database file itself to disc since it has been there all along. Only the current record is in memory at any one time and this is automatically written back to disc when it has been changed in any way. If you are going to use another database straight away just double click on it or drag it to the Powerbase icon on the icon bar. In fact you don't even need to close the previous database before doing this; Powerbase will do it for you. When working with a database on the RAM disc Powerbase will issue a warning that the data is not secure and that you need to drag it from the RAM disc to a floppy or hard disc before switching off. To terminate Powerbase itself use the Quit option on the icon bar menu.