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WELCOME TO dBASE IV 1.5 ----------------------- This file contains important information that is not contained in the documentation for dBASE IV 1.5. All information in this file supersedes information in the dBASE IV 1.5 documentation. TABLE OF CONTENTS ----------------- 1. Notes on Queries 2. Notes on DBHEAP 3. Creating User-defined Help 4. Creating Pop-ups for Data Validation 5. Guidelines for Interrupts 6. Changes to the REPLACE FROM ARRAY Command 7. Notes on HyperDisk 8. REPLACE ON <keyfield> in a Network Environment 9. Reinstalling Printer Drivers 10. Installing dBASE IV RunTime on a Network 11. Installation Notes for Network Access Pack Users 12. Using dBTUTOR on a Network 13. Notes for Banyan Vines Version 4.10 Users 14. Specific Documentation Corrections 15. Guidelines for Using the Design and Data Surface Programs 16. Notes on DBSETUP 1. NOTES ON QUERIES ---------------- Using IQ! to Optimize Queries: IQ! is Borland's exclusive automatic Index Query optimization technology embedded within QBE. To use IQ!: 1) Make sure you have a database open, and then select the Queries Design tool from the Control Center. 2) Select the Fields menu. 3) The Filter Method option on the Fields menu offers 4 choices: OPTIMIZED, SET KEY, INDEX...FOR, and SET FILTER. Select OPTIMIZED by pressing the Spacebar or Enter key. 4) Press the Esc key to return to the Queries Design tool. OPTIMIZED automatically selects the fastest method for processing your query among the three filter methods (SET KEY, INDEX...FOR, or SET FILTER). Linking and Sorting Operations: QBE linking and sorting operations on calculated fields involving more than one database file are not supported. If you use a complex calculated field involving more than one database file in QBE and try to link or sort on this field, you'll get the following error message: "Operation not allowed for calculated fields" Creating Links with the Mouse: On the Queries Design screen, you can create links by pointing with the mouse. The mouse cursor alone does not create links, but you can use the mouse to position the keyboard cursor. Click on the F3/F4, Shift-Tab, and Tab keystroke identifiers (also known as "hotkeys") on the navigation line to move the keyboard cursor into the field you want to link. When you've positioned the keyboard cursor into the linking field, click on the Enter hotkey. 2. NOTES ON DBHEAP --------------- The following information corrects the DBHEAP section on page 2-12 of the Getting Started manual: DBHEAP is a DOS environment variable that you set at the DOS prompt before you start dBASE IV. DBHEAP tells dBASE how much of the RAM available after loading dBASE should be reserved for memory-intensive operations. The syntax is: SET DBHEAP=<expN> where <expN> is any value from 1 to 100. The default is 50 (if you set it to 0, it will default to 50). This number represents a percentage of available space (a value of 30 means that dBASE will use only 30% of the available RAM for memory-intensive operations, and will allocate the remaining 70% for code overlays). Memory-intensive operations include indexing, sorting, and using memory files (such as windows, arrays, menus, memory variables, and so on). The amount of memory available after dBASE is loaded really depends on your particular hardware configuration and the application you're running. The best way to fine-tune DBHEAP is to run an application using the default setting (50), then run it again with higher and lower DBHEAP settings to see if the application runs faster. Suggested low/high settings to start with are 30 and 70 (the useful range is between 20 and 80). 3. CREATING USER-DEFINED HELP -------------------------- The Form.gen template file lets you create user-defined Help frames. The F1 Help key can now provide user-defined help information for individual fields on the Edit screen. When you press F1 Help, the information in the memo fields of a special database file will display in a pop-up Help window. If you want to create your own Help file, create the special database file described below. The name of the database file must begin with the first six characters of the name of the format file, followed by "_h.dbf". For example, if the format file is called Entry.fmt, then the Help file must be called Entry_h.dbf. The database file must be created with the following structure, before you compile the form: Field Field Name Type Width Dec Tag ----- ---------- --------- ----- ---- --- 1 FLD_NAME Character 10 Y 2 FLD_HEADNG Character 25 N 3 FLD_HELP Memo 10 N ---------------------------------------------- Enter the names of the fields for which you want help in the Fld_name field. You need to create an index tag named Fld_name, as follows: INDEX ON UPPER( Fld_Name ) TAG Fld_Name You do not need to include all the fields from the database in the Help file, only the ones for which you want Help windows. Enter the character string for the top frame of the Help window in the Fld_headng field. Enter the Help text you want displayed for each field in the Fld_help memo field. If there is more text than will fit inside the help window, navigation instructions are displayed inside the Help window. 4. CREATING POP-UPS FOR DATA VALIDATION ------------------------------------ Using CREATE/MODIFY SCREEN, you can create a data validation routine that presents a pop-up displaying the valid choices from a lookup database file when a user enters a value that does not match the lookup file. To create a pop-up for data validation, start from the "Accept value when" portion of a field's Edit Options table on the forms design screen. You must enter the following syntax (including quotes): "POPUP"="<database>-><fieldname> ORDER <fieldname> [REQ] [SHADOW]" For example, to validate the Vendor_id field in Goods.dbf against the Vendor_id field in Vendors.dbf, insert the following pop-up string in the "Accept value when" fill-in when highlighting the Vendor_id field in a form that uses Goods.dbf. "POPUP" = "Vendors->Vendor_id ORDER Vendor_id REQ SHADOW" If you want to attach an additional .AND. condition to the pop-up validation, include the condition after the "POPUP"="..." expression. The condition should not be delimited with quotes. The components of this pop-up string are: POPUP Initiates pop-up processing for this field during EDIT. Vendors->Vendor_id Indicates the database file to open and the field in that database file to use for data validation. You must have an index tag on this field. ORDER Vendor_id Specifies the index tag that orders this field. REQ Shows that the user must enter something into the field before moving on. This is optional. If REQ is omitted, the user can escape the pop-up and leave the field blank. SHADOW Provides a shadowing effect underneath the pop-ups. SHADOW is optional. You can use a field from the .DBF file you are currently working with or a .DBF from another work area. However, the validated file and the lookup must be different files. Pop-ups are usually displayed below the currently-highlighted field, unless the current field is low on the form. Limitations of Pop-up Validation: - This feature is designed for EDIT and might not display as smoothly in BROWSE. If you have a pop-up on your EDIT, the F2 toggle from EDIT to BROWSE is disabled. - Pop-up validation cannot be used on a multiple choice field. - Pop-up validation cannot be used on a form created by using a view that contains more than one file. - In order to protect a procedure file you currently have in use, EDIT will close it on entry and reopen it on exit. If this presents a problem with forms that use procedures, see SET LIBRARY in the Language Reference manual, and Sysproc and SET LIBRARY in the Programming in dBASE IV manual. - The first six characters of the form name and the first eight characters of the field names with these pop-ups must be unique. 5. GUIDELINES FOR INTERRUPTS ------------------------- You can write or use dBASE applications in which commands or full screen operations are interrupted with another command or function. Please carefully review the extensive discussion of interrupt handling in the FUNCTION command section of the Language Reference before attempting to program any interrupt handlers of your own. Additional guidelines follow for specific situations. Restoring the Record Pointer: An important situation that is not discussed in the Language Reference manual occurs when an interrupting command or function moves the record pointer of the original database file. Each open database file has an associated work area in which one of the data items, the record pointer, tells dBASE IV which record is the active record. When executing an interrupt routine, dBASE does not automatically save and restore the various work areas' current record pointers, regardless of the DBTRAP setting. In every work area, whichever record is active at the end of an interrupt remains the active record. To ensure that an interrupted process (such as BROWSE) resumes smoothly after an interruption, all record pointers for the originally-active database files must be returned to the values they had just prior to interruption. Because dBASE IV does not do this automatically, your interrupt functions or procedures should take explicit steps to ensure that all record pointers are restored to their original values. You can determine the value of the record pointer for each work area with the RECNO() function. Following is a typical example of how to move the record pointer in dBASE IV (with the GO command), and how to ensure that the interrupted process resumes smoothly: FUNCTION myudf(...) oldrecno = RECNO() [the rest of your interrupting code here] GO oldrecno RETURN Replacing APPEND Values: If you write code or use an application that moves the record pointer during an interruption, (see the item above), you must take special care when you're executing the interrupt during the full-screen APPEND command. Whenever you interrupt APPEND, you should restore the record pointer as mentioned in the previous item. In addition, your interrupting code must save (on entry) any values entered onto the APPEND screen prior to the interruption. You must then restore these saved values after the record pointer is repositioned (just before the interrupt routine exits). These steps are required because dBASE IV keeps all values entered during the APPEND command in a temporary buffer. During APPEND, the buffer record values are handled as follows: - If you press Esc and abandon the new record, the values are discarded. - If you accept the new record during a normal APPEND, the values are added to the database file as a permanent record. However, when the record pointer is moved during an APPEND interrupt, the values in the temporary record are not retained (they become blank). Although the APPEND screen may show the values as they were originally entered, those values are no longer in the temporary buffer. A common occurrence of this is during an interrupt call to a validation UDF which uses a SEEK to check for duplicate keys. SEEK will reposition the database, changing the current record pointer and blanking the temporary buffer. The following example illustrates the proper steps for your APPEND interrupt code. These steps ensure that the values entered before an interrupt are preserved after the interrupt. Note that this example saves previously-entered memo fields. 1) Save the current record number. oldrecno = RECNO() 2) Save any values already entered. numfield = FLDCOUNT() DECLARE Fldinfo[numfield,2] n = 1 DO WHILE n <= numfield IF Field(n) # "_DBASELOCK" && Don't save _DBASELOCK Fldinfo[n,1] = FIELD(n) IF TYPE( Field(n) ) = "M" && Save memo text to file SET SAFETY OFF COPY MEMO &Fldinfo[n,1] TO LEFT(Fldinfo[n,1],8)+".xxx" SET SAFETY ON ELSE Fldinfo[n,2] = &Fldinfo[n,1] ENDIF ENDIF n = n+1 ENDDO 3) Perform the rest of the interrupting code. [Whatever you want it to do] 4) Return to the original record number. GO oldrecno 5) Restore the previously-entered field values. n = 1 DO WHILE n <= numfield IF Field(n) # "_DBASELOCK" IF TYPE( Field(n) ) # "M" && Restore memo text later REPLACE &Fldinfo[n,1] WITH Fldinfo[n,2] ENDIF ENDIF n = n+1 ENDDO Memo fields cannot be restored using the REPLACE command during an APPEND interrupt. You can restore the memo field data from the files written to disk with the code shown above. These files have names created from the field names such as LEFT(Fldinfo[n,1],8)+".xxx". If your interrupting code deliberately changes the initial field values entered into APPEND, you will need to modify the sample code shown here so that it fills those fields with their final values, not the initial values the fields had before the interrupt. Using Fields Lists: dBASE IV lets you restrict the fields on which some dBASE IV commands operate. (See the SET FIELDS command in the Language Reference manual for a list of commands affected by the fields list.) You can use a fields list in two ways: 1) You can provide a temporary fields list when executing a command: BROWSE FIELDS Lastname, Firstname, City A temporary fields list cannot reference any fields outside the global fields list (if SET FIELDS is ON), and it does not affect the global fields list. 2) You can set up a global fields list with the SET FIELDS command: SET FIELDS TO Lastname, Firstname, City Once you have established the global fields list, you can change it in two ways: 1) By executing the SET FIELDS or CLEAR FIELDS commands. 2) By closing a database file containing fields in the fields list. dBASE executes these commands at any time, without any restrictions, including executing them within an interrupt routine. However, changing the fields list within an interrupt routine can prevent the interrupted command from finishing correctly. If your interrupt routine interrupts a command that uses a fields list, do not use these actions (SET FIELDS, CLEAR FIELDS, or closing a database file containing fields in the fields list) to change or discard the global fields list during the interruption. 6. CHANGES TO THE REPLACE FROM ARRAY COMMAND ----------------------------------------- In dBASE IV 1.1, a one-dimensional array replaced the records within the scope that met the condition. However, REPLACE FROM ARRAY...ALL replaced only one database record. In dBASE IV 1.5, a one-dimensional array will replace the first record in the database file that meets the scope condition. To replace more than one record in the database file with the elements of a one-dimensional array, you can use a DO WHILE structure. For example: *--- Using the CONTACTS database, assign a new area code to the *--- city of 'TORRANCE', and a new sales rep 'Samuel Smith'. DECLARE New_Code[2] New_Code[1] = '310' && New area code New_Code[2] = 'Samuel Smith' && New sales rep USE Contacts DO WHILE .NOT. EOF() IF Area_Code = '213' .AND. City = 'TORRANCE' REPLACE FROM ARRAY New_Code FIELDS Area_Code, Sales_Rep ENDIF SKIP ENDDO For further information on using REPLACE FROM ARRAY, please see the dBASE IV 1.5 Language Reference manual. 7. NOTES ON HYPERDISK ------------------ To improve performance on PCs with extra memory, dBASE IV 1.5 supports the optional use of the HyperDisk disk caching program, which is provided as a standard dBASE software component. Following are known incompatibilities with the HyperDisk program. Incompatibilities with Automatic Compression Programs: The HyperDisk cache program and various automatic disk compression programs, such as Stacker and SuperStor, conflict in their management of low-level disk I/O, leading to a fundamental incompatibility. If the dBASE HyperDisk cache is active when dBASE is used to access data on a compressed logical drive managed by Stacker or SuperStor, the compressed logical drive will most probably become corrupt and unusable. If you are already using Stacker or SuperStor or any other automatic compression program, disable the dBASE HyperDisk cache program. To do this during dBASE installation, select the option of not using the cache. If dBASE is already installed and you want to begin using an automatic compression program, disable the dBASE cache first. To do this, go to the drive and directory in which dBASE is installed and enter the command: CACHEDB OFF This will disable the dBASE HyperDisk cache and eliminate the conflict. Incompatibilities with Microsoft Windows: If you're running dBASE IV in Microsoft Windows, disable the HyperDisk cache as shown above and use the version of Smartdrv.sys provided with Windows. 8. REPLACE ON <keyfield> IN A NETWORK ENVIRONMENT ---------------------------------------------- Replacements on key fields of an indexed database file also update the index file if it's in use. When the replacement is made, the record moves to a new position in the index file if the index is active. If you specify a scope, a FOR, or a WHILE when making replacements on an indexed field, (and the index is active) all the records you intended may not be replaced. For example, if you REPLACE ALL, only the first record and those that follow the new key field value will be replaced. To replace all the records, you should either put the database in natural order by entering SET ORDER TO or use the database exclusively with USE <database name> EXCLUSIVE. 9. REINSTALLING PRINTER DRIVERS ---------------------------- Some printer driver names, such as Ibmpro.pr2, have been changed in dBASE IV version 1.5. If you are using IBMPRO printers, reinstall the printer drivers using DBSETUP. If you run dBASE IV 1.5 with your old Config.db file, you might get an error message like "File not found" indicating that the printer driver could not be found. If you get this message, use DBSETUP to reinstall the new versions of your printer drivers. 10. INSTALLING dBASE IV RUNTIME ON A NETWORK ----------------------------------------- dBASE IV RunTime is a separate package that lets you distribute compiled and (optionally) linked object code files as a stand-alone application. If you own the RunTime package and install it on a network, be sure to mark the following files read-only (use the DOS ATTRIB command): Runtime.res Runtime.ovl 11. INSTALLATION NOTES FOR NETWORK ACCESS PACK USERS ------------------------------------------------ If you install single-user dBASE and later purchase the Network Access Pack to support additional users, make the following changes after running ADDUSER4: 1) Delete the EXCLUSIVE = ON statement from your Config.db file 2) Mark the following files read-only (use the DOS ATTRIB command): dBase1.res dBase2.res dBase3.res dBase.ovl You should also mark these files read-only after running dBaseovl.bat on a network. 12. USING dBTUTOR ON A NETWORK -------------------------- You can run dBTUTOR on a network only if you disable your network's message protocol. Otherwise, your computer will hang if a message notice interrupts the dBTUTOR program. 13. NOTES FOR BANYAN VINES VERSION 4.10 USERS ----------------------------------------- Unless you enable NetBIOS extensions, Banyan Vines version 4.10 will return a null value for dBASE's ID(), LKSYS(2), and LKSYS(5) functions, and for the DISPLAY USER command. In addition, dBASE users attempting to BEGIN TRANSACTION will receive error message #183, "Unterminated transaction file exists, unable to start transaction." If you enable NetBIOS extensions (a TSR), Banyan will return a NetBIOS User ID that dBASE can use. To enable NetBIOS extensions, add the following to the Autoexec.bat on the workstation: SETNETB /Name:<nodename> where <nodename> is the name you want dBASE IV to use. This name can be your Banyan login name. To avoid conflicts in dBASE IV, verify that the nodename is unique for all dBASE users. If you have problems enabling NetBIOS extensions, contact your Banyan Network Administrator. 14. SPECIFIC DOCUMENTATION CORRECTIONS ---------------------------------- Following are corrections to the Language Reference manual. Page 2-133, IMPORT IMPORTing a PFS file will also create a .vue file. Page 2-144, KEYBOARD Table 2-9, Supported Key Labels, should include the following note: You cannot use {Enter} or {Esc} with the KEYBOARD command. To send an Enter key, use either {Ctrl-M} or {13}. To send an Esc key, use {27}. You can continue to use the CHR() function with these values. Page 2-189, QUIT The <expN> value can be an integer between -(2^31)+1 to (2^31)-1. dBASE will return to DOS a value based on the value of MOD({return}, 256) to yield a number in the range of 0 to 255. Page 2-228, TOTAL The first paragraph on this page states "The structure of the TO file is the same as the active database file as limited by FIELDS, except that memo fields are not copied to the new file." Actually, the FIELDS option limits only the fields that are actually totaled. To limit the fields in the TO file, use the SET FIELDS TO command. Page 3-46, SET FILTER TO Using the optional [FILE <filename>/?] parameter and the [<condition>] parameter are mutually exclusive. Correct the syntax as follows: SET FILTER TO [ FILE <filename>/? ] / [ <condition> ] Page 3-50, SET FUNCTION The range of values accepted for the numeric key assignment, <expN>, is omitted. The range is between 2 and 29. Page 3-58, SET KEY Correct the syntax as follows: SET KEY TO [ <exp:match> / RANGE <exp:range> ] [ IN <expWA> ] where <exp:range> ::= <exp:low> , <exp:high> <exp:low> [ , ] , <exp:high> The syntax and the values shown for the range in the SET KEY example on page 3-59 are wrong. Correct the example as follows: . USE People . INDEX ON Zip TAG Zip . SET KEY TO RANGE '60000' , '90000' . BROWSE Page 3-60, SET LIBRARY TO The <filename> parameter is optional. SET LIBRARY TO with no filename will close the active LIBRARY file. Correct the syntax as follows: SET LIBRARY TO [ <filename> ] Page 3-73, SET PRINTER TO The <DOS device> parameter is optional. If the device name is missing, SET PRINTER TO will reset the printer to the default DOS printer device. Correct the syntax as follows: SET PRINTER TO [ <DOS device> ] Page 3-98, SET WINDOW The <window name> parameter is optional. If you do not include a window name, the window for the memo field is reset to none. Correct the syntax as follows: SET WINDOW OF MEMO TO [ <window name> ] Page 4-12, CALL() Correct the syntax as follows: CALL( <expC>, <expression> [, <expression list>] ) Page 4-141, TAGNO() Correct the syntax as follows: TAGNO( [ <order name> [, <mdx name> [, <alias> ]]]) 15. GUIDELINES FOR USING THE DESIGN AND DATA SURFACE PROGRAMS --------------------------------------------------------- In order to maintain the integrity of the Control Center and the user's design surface session, your surface program should keep track of the following settings and restore them upon completion: 1) Catalogs The foundation of the Control Center is the catalog file. When returning from a surface program, ensure that you return control to the original catalog file. Commands like CLEAR ALL, CLOSE ALL, and SET CATALOG TO will close the active catalog file. If you use these commands, you must reset the catalog file before ending the surface program. Use the CATALOG() function to save the current catalog, then restore it when ending the surface program. 2) Database files Commands like USE, CLOSE DATABASES, CLOSE ALL, and CLEAR ALL will close an open database file. If you use these commands in your surface program, you must reopen any database files that were in use before the surface program was launched. Use the DBF() function to save the name of any database files in use, then restore them when ending the surface program. Note: If DBTRAP is ON, and a database file was at the beginning of the surface program, CLOSE ALL, CLOSE DATABASES, and CLEAR ALL will leave that one database file open. 3) Indexes Certain design surfaces, such as the queries design screen, rely on indexes associated with the user's database files. If your surface program deletes an index that was associated with a database file in use when your surface program was launched, then you must recreate the index before returning to the design surface. Use the MDX(), NDX(), and KEY() functions to save the name and key expressions of any indexes, and then recreate them when ending the surface program. 4) Work area In your surface program, you can move to other work areas and open and close files in these other work areas. Unless you are using a custom Form, Report, or Label.gen, you must be sure to return to the original work area before your field or layout program returns to the design surface. Use the SELECT() function to save the current work area, then reselect it when ending your surface program. 5) The screen Through the use of surface programs, you are given complete control of the design and data screens. Your program can clear the screen and add any output you want into it. When returning to the surface, dBASE does not automatically repaint the screen for you. If you want to maintain the user's screen, use the DEFINE WINDOW and ACTIVATE WINDOW commands in the beginning of your surface program, do any screen output, then issue a DEACTIVATE WINDOW command before returning to the surface. Another way to save the surface screen is to issue a SAVE SCREEN command at the beginning of your surface program, then a RESTORE SCREEN command at the end. 16. NOTES ON DBSETUP ---------------- If you alter or create your Config.db using DBSETUP, do not enter commas into any of the following Files menu options: Prgapplic Prgbrowse Prgcc Prgdata Prgedit Prgform Prglabel Prgquery Prgreport