ProfitPress Mega CDROM2 Shareware Freeware (MSDOS)(1992)(Eng)

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Text File | 1991-04-03 | 13.9 KB | 263 lines

EDB Ed's Data Base Copyright 1991 Ed Hand This file is in two sections. The first deals with the use of EDB.EXE. The second section goes into detail on the format of the form file and how to write your own form files. Section One: How to get around in EDB EDB is a database whose format is defined by an ascii form file. The form file has an extension of ".frm". The fields of a form can contain simple static information for display or accept any format of input. Execution of EDB is simple. The name of the form file is given on the command line with no other arguments. For example: EDB PHOTO This will start EDB and try to open a file named "PHOTO.FRM". If the file cannot be found in the current directory EDB will issue an error and halt execution. If the file is successfully opened then EDB will read the form description, draw the screen and then allow you to start processing. To run EDB the only files needed are the executable EDB.EXE and a form file. Once EDB has been started you will see a working screen. You will stay at this screen for the entire program. All commands are available from an options menu at the top of the screen. There are several ways to select a command. You may use the arrow keys to move the cursor around to the different commands. Or for most commands you may simply enter the first letter of the command and EDB will move the cursor to that command. The only exception to this is the compress command. To move to the compress command enter the letter "O", the second letter of the word. Once the command is highlighted press enter to select the command. Users of emacs can also use standard emacs cursor commands to move the cursor: Cntrl-P and Cntrl-B move to the previous command. Cntrl-F and Cntrl-N move to the next command. Note that the emacs commands only work on the options menu. If you are editing a field and enter a control character it will be entered as part of the data. More on that later. From the options menu you may also use Cntrl-R or Cntrl-L to redraw the screen. This is useful if an ill behaved TSR pop-up doesn't repaint the screen upon exit. The EDB options commands are as follows: Exit - Exit the current session and return to the dos prompt. Add - This function places the user in the first field of the form and accepts data until the user exits the form. The data is then stored as the next entry in the database. If the specified database file does not exist then EDB will issue an error and toss the entered data. If a database does not exist the add function does NOT try to create it. Create - This option is used to create a new database file. The cursor will be placed in the form at the location of the field used to hold the filename. After the user provides a filename EDB will create a file of the form <filename>.EDB and put a standard EDB header on the file. This option must be used before an add may be performed. If the named file already exists then EDB will not create the new database file. Search - This option puts the user in the form and lets him enter data into any/all/none of the fields. After the user exits the form any fields that had data entered in them will be used for search criteria. The only field that requires a value to be entered is the field that holds the database file name. If the rest of the fields are left blank then all rows will be found. Modify - After a search has completed, the retrieved data may be modified with this command. The user will be placed in the form and allowed to edit any field desired. If the user edits the name of the database file then EDB will try to add the entry to the newly named file, if it exists. If it writes the entry to the new file then it will also set the delete bit on the entry in the old file. Next - Moves to the next row found by search or find. Previous - Moves to the previous row found by search or find. Delete - This row will set the delete bit for the current record. It will first ask for confirmation before marking the record as deleted. Report - This row will prompt for a file name and then write a copy of each record in the current search list to the file. If no file name is given EDB will default to <formname.RPT>. There are two choices for the format of the report. You may select either a comma separated list or a file with one line for each field using a "<field prompt>: <data value>" format. Compress - This option will compress a database file by removing all entries with the delete bit set. It does this by creating a temporary file and reading all non-deleted entries to that file. Upon successful completion EDB will then rename the old database to <filename.old> and rename the temporary file to <filename.EDB>. Thus if there are any errors during the compression the original file will be left intact and in place. Find - This option is the same as search with one exception. This command will find matching entries even if they are marked as deleted. Undelete - This is the opposite of delete. If a row is deleted by mistake or for any reason needs to be made active after a deletion this option will clear the delete bit for that row. The find command must be used to locate a deleted row since search ignores deleted records. When entering data into fields EDB requires that a carriage return be entered for the data to be accepted. To exit a form the user must enter an escape character as the first character in a field. If the user enters ANY character after a normal displayable character in a field, that character will be accepted as data. To exit a form the user must enter a carriage return to get to the next field if any data has been entered in the current field. Then an escape may be entered to keep the data or a CNTRL-C may be entered to cancel the current operation. Section Two: Form File Syntax The form file is a simple ascii file that describes how to draw the screen. Any form of white space may separate the fields in the form file. A form field description may contain several fields in the form file. The first field of the file is a single integer. This is the number of form fields described in the file. The rest of the file describes the actual fields of the database. There are six different types of form fields. Each form field definition starts with a letter that identifies that fields type. The letters are "a", "d", "i", "l", "D", and "T". After the identifying character each field description is followed by an x and y coordinate value. These two values tell EDB were on the screen to put the first character of the fourth parameter of the field. The fourth parameter is a quoted text string. In most cases this string acts as a prompt for the field. In one case this string is just static information to display at some point on the screen. If you don't want a prompt then define this as a null field (ie. ""). Some fields require a fifth parameter. This is a data type parameter. It tells what kind of data the field holds. Valid values for this option are: i - An integer value. All integers are stored as a 32 bit value in the database. f - A floating point value. All floating point numbers are stored as doubles. s - A string. Strings are stored at whatever length the field is defined to be, padded if needed. The sixth parameter, for fields that need it, is the field length. It defines the number of characters allocated on the screen for a field. Please examine the sample form files delivered with this product for examples on how to implement a form file. The syntax for each field type follows. Type = a Syntax - a <x> <y> <"prompt"> <data_type> <length> This is a special field. There may be only one in any form. Each time you add a new record to a database with this field in the form, this field will automatically increment. This field must be of data_type integer. When modifying records created with a form using this field, this field may not be modified. Type = d Syntax - d <x> <y> <"prompt"> <data_type> <length> [places] This is a standard data field. Most fields in a form will be of this type. These fields can have a data_type of integer, floating point, or string. If this field has a data_type of floating point then you must also specify the number of decimal places to display on the screen. Otherwise the "places" parameter is left blank. Type = i Syntax - i <x> <y> <"text"> This is a static information field. It is used to place a string of text on the screen that will not change. It is useful for placing a name over a subsection of a form. Type = l Syntax - l <x> <y> <"prompt"> This is a location field. It is used to hold the name of the database file to use. The idea here being that the same form can be used with several files. Note however, when doing a search or find only one filename can be used. Searching of multiple files is planned as a future feature. Each form may contain only one location field. Type = D Syntax - D <x> <y> <"prompt"> This is a date field. It holds a four byte structure that is a date. If the first and only character entered in this field is a "T", then EDB will return the current date. The way the date is displayed is dependent on your country code. If you don't have country.sys running or country is set to U.S. then the date is displayed as "mm/dd/yy". The date will display as "dd/mm/yy" for european users and as "yy/mm/dd" for asian user if country.sys is properly installed. Please note that you must enter a date in the same format it is displayed in or EDB will get confused. At this time there is no check to insure a valid date. Type = T Syntax - T <x> <y> <"prompt"> This is a time field. It is identical to the date field but holds a time stamp instead. As with the date field, a "T" will return the current system time. Now for the limiting factors. No more than thirty-two fields per form. No more than one screen per form. In other words, your form cannot be more than eighteen lines long. However, this is something I plan to change in the future. The suggested working area for the screen is from lines six through twenty-three inclusive. And columns two through seventy-nine inclusive. Well, if you find any bugs or problems let me know. Also if you have any suggestions or ideas feel free to send them to me also. My INTERNET address is: hande@infonode.ingr.com