A User Guide for the RAQUEL GUI
Contents
1. are greyed out are not yet implemented Page 1 of 5 User Guide for the RAQUEL GUI 19 November 2009 David Livingstone Richard Ockerby 2 By hitting a menu option the RAQUEL syntax for that option is generated in the Editor frame This saves on typing input and eliminates the need to know the precise syntax of every relational operator assignment The leftmost column contains two menus an upper Assignments menu and a lower Operators menu Assignments This has 4 items Clicking on a menu option gives rise to a submenu which appears to the right hand side of the Assignments menu The previous illustration shows the submenu resulting from choosing the Value option Clicking on a submenu item inserts the corresponding RAQUEL syntax into the Editor frame The 4 submenus are 1 The Value Assignment submenu This consists of all the assignments that assign the relational value relvalue on their RHS to the named relational variable relvar on their LHS 2 The Constraint Assignment submenu This consists of all the assignments that assign an integrity constraint to the named relvar on their LHS 3 The Binding Assignment submenu This consists of all the assignments that assign a binding to the named relvar on their LHS where the binding is of a relvar to its physical storage This subset of RAQUEL is not part of the logical relational model but a means whereby the Database Administrator ca2. User Guide for the RAQUEL GUI 19 November 2009 David Livingstone Richard Ockerby A User Guide for the RAQUEL GUI Introduction The layout of the RAQUEL GUI is shown below It can vary in detail due to different screen aspect ratios and subsequent updates 10 Options Cut Copy Pas F Execute Assignments Value Value Constraint Retrieve Physical Binding Real f e E Operato e Insert Delete Ee E Generalised Join Left Semi G Join Right Semi G Join Left Outer G Join Right Outer G Join Full Outer G Join Natural Join Left Semi N Join Right Semi N Join Left Outer N Join Right Outer N Join Full Outer N Join a Project Restrict asl ST 7 NT 7 The RAQUEL GUI is also known as the RAQUEL Teaching Tool Overview of the GUI s Functionality The upper centre frame of the GUI is where RAQUEL statements are written to be executed the Editor frame The lower centre frame is where an executed statement is copied together with a message to say that it executed OK or alternatively what the error was if it failed the OK Error frame The right hand frame is where the results of a retrieval statement are displayed the Results frame The left hand menus serve two purposes 1 To act as a reminder of what relational operators and assignments are available in RAQUEL Those with black lettering can be executed by the DBMS those that
3. n assign physical storage to relvars 4 The Database submenu This consists of all the operators and assignments that refer to database schemas Operators This menu comprises all the RAQUEL relational algebra operators It may include a vertical scroll bar if the screen size warrants it Clicking on a menu option inserts the corresponding RAQUEL syntax into the Editor frame Upper Centre or Editor Frame As well as being able to type text into the frame and use the menus to insert text the frame incorporates a simple editor that operates on text highlighted in the frame using the Cut Copy and Paste buttons on the menu bar or CRTL X CTRL C and CTRL V key combinations respectively in the usual way Note that text input by a menu option can be edited in the same way as any other text it is only conventional text that is inserted by the menu option Text can be deleted by putting the cursor to the right of it and using the backspace delete key use of the Delete key has not been implemented Statements that have been completed are executed by hitting the Execute button on the menu bar or using the CTRL Return key combination The cursor does not need to be at the end of a statement when hitting the Execute button Page 2 of 5 User Guide for the RAQUEL GUI 19 November 2009 David Livingstone Richard Ockerby or CTRL Return the cursor may be anywhere within the Editor frame and the whole stateme
4. nt will be executed Hitting the carriage return key starts a new statement on a new line of text but does not execute a statement Word wraparound automatically occurs those lines of a statement that follow the first are automatically indented so that the whole of an individual statement can clearly be seen A single statement may take up as many lines as desired Where a whitespace character is required more than one whitespace character may be used each being any kind of whitespace character space tab or carriage return Statements that have not yet been executed appear in black Once they have been executed they are greyed out Greyed out statements or parts thereof can be copied and pasted into new black statements Lower Centre or OK Error Frame This frame is only used for displaying the text of an executed statement and whether it executed correctly or the error on which it failed Right Hand or Results Frame If the statement is not a retrieval statement nothing is displayed there although a blank line is output to indicate a nil return The frame is regarded as a named Sink into which relvalues can be put The sink knows how to display relvalues on the screen as long as it Knows how to display values of all the attribute types appearing in the relvalue These types are currently numbers text and truth values The sink frame has the name s lower case Thus all statements that are to retrieve
5. output flows of statements results to and from the GUI They are deliberately not called File options because the focus of the options is I O not files and to avoid any confusion of the notion of files with the notion of a database The same set of options applies to both statements appearing in the Editor frame and results appearing in the Results frame Clear Clear amp Insert from File Insert from File oave to File Clear Clear amp Insert from File Insert from File save to File Exit The options can be summarised as Clear This clears away all the current contents of the frame outputs them down a black hole sink Clear and Insert from File This clears away all the current contents of the frame and then inputs into the frame all those statements results held in a specified file Insert from File This inputs into the frame all the statements results held in a specified file putting them after the current contents of the frame Save to File This outputs to a specified file all the statements results currently in the frame Further details are as follows Clicking on the Clear and Insert from File or the Insert from File menu option results in a dialogue box in which the name of the specified file can be entered Page 4 of 5 User Guide for the RAQUEL GUI 19 November 2009 David Livingstone Richard Ockerby RAQUEL Fileselection E Clear amp Inser
6. relvalues into the Results frame must have S lt Retrieve immediately to the left of the relational expression that is to be evaluated and retrieved Menu Bar Options Button 1 An option to display error messages in English or French The French option has been switched off greyed out as it is only partially operational Additional languages are intended in future 2 The Set Maximum Attribute Display Width option The columnar spacing used to display attribute values in the Results frame varies automatically so that each column is no wider than is necessary to display the attribute name and the longest attribute value in the result plus a single column divider space The maximum possible column width allowed is 50 characters by default This option can be used to reduce the maximum column width Any reduction only lasts till the end of the session or until it is changed again N B A potential future orthogonal option is to permit several classes of error message for each error where classes vary in their terseness with increasingly verbose messages giving increasing degrees of help in how the error might be overcome Page 3 of 5 User Guide for the RAQUEL GUI 19 November 2009 David Livingstone Richard Ockerby Menu Bar I O Button As well as providing the Exit option this button provides options for managing RAQUEL statements and the results of retrievals in the GUI The focus is on using input and
7. t from File Insert from File File lyetMore Examples File more Examples Highlight a file name on the left and its name will appear in the upper box Click on OK to copy the contents of the named file into the relevant frame the same functionality applies to both statements and results Clicking on the Save to File menu option results in a similar dialogue box E RAQUEL Fileselection O X save Results to File File example Results f example Results OK more Results yetMore Results Cancel A new file name can be entered in the upper box or a file name selected from the left hand side Click on OK to save the contents of the relevant frame into the named file again the same functionality applies to both statements and results If the name of an existing file is chosen then its entire contents are overwritten by the complete contents of the frame The files themselves are held in Saves which is a subdirectory of the directory in which the RAQUEL GUI software is held Files containing statements are held in the Statements subdirectory of Saves and those containing results in the Results subdirectory of Saves The file paths are displayed near the top of the dialogue box Page 5of 5
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