PRODUCT:  R:BASE                               VERSION:  4.5+ or Higher
     CATALOG:  Forms, Reports & Labels              AREA   :  Forms
     Many users want to see a running total display as rows of data are entered 
     in a region. This has been doable since R:BASE 3.1 and the introduction of 
     EEPs to forms. However, now using some of the R:BASE 4.5 Plus! features, it 
     is so easy anyone can do it. Minimal programming is required, the EEP code 
     is straightforward and simple.
     Prior to R:BASE 4.0 and the addition of the SCREEN RESTORE command a field 
     had to located on the form to display the calculated total. Because of 
     region field location rules, it had to be located on every row in the 
     region, or outside the region and associated with a separate table. Using 
     SCREEN RESTORE OFF allows variables displayed by a WRITE statement in an 
     EEP to remain on the screen; the screen is not refreshed when returning to 
     the form from an EEP. 
     The summing technique using SCREEN RESTORE OFF calculates the total in the 
     EEP and writes it to the screen. It is no longer necessary to locate a 
     variable on the form to hold the total. And R:BASE 4.5 Plus! has added the 
     SAVEROW EEP only command which provides even more options for the 
     application developer.
     This article shows two different methods for displaying a running total 
     as new rows are added in a region. They are slightly different, choose 
     the one that works best for your situation. One uses a field level EEP, 
     the other a table level EEP. There are pros and cons to each as discussed below. 
     Some elements are common to both methods. The total is displayed on the 
     screen using a WRITE command. To determine the correct screen location for 
     the WRITE command, bring up the form in Create/modify mode. Place the 
     cursor in the exact place you would like the total to be written. Add 1 to 
     the row number displayed. The column number to use is where you want the 
     left side of the value to display. These are the coordinates to use in the 
     WRITE command. In addition, you need an EEP on the first table in the form, 
     On entry into a row, to clear the screen location where the total is 
     displayed. For example, 
     CLS FROM 22,35 TO 22,79
     You must include SCREEN RESTORE OFF in this EEP. It makes sure the screen 
     is refreshed as you add rows. 
     Using a table level EEP
     The table level EEP is placed On exit from a row on the Table settings 
     screen for the region. It uses an accumulator variable, vsumprice, to 
     accumulate the total as rows are added. You define a form variable to 
     calculate the extended price on each row. This variable passes that row 
     value to the EEP where it is added into the running total. In this example, 
     using the sample form, tranform, from the Concomp database, the variable is 
     already defined on the transdetail table, the variable vextprice. 
     SET VAR vsumprice CURR = (.vsumprice + .vextprice)
     WRITE .vsumprice AT 22,62 YELLOW ON BLUE
     This is a simple, forward processing EEP. It does not take into account a 
     user moving back to a previous row or a user discarding a row of data. An 
     incorrect total may display in those situation. Also, this is not a good 
     choice when editing data. As you move forwards and backwards through the 
     rows in the region, the EEP executes and keeps adding to itself. These 
     situations can be corrected by trapping for keystrokes, however. For 
     example, the following code added to the beginning of the EEP will not 
     recalculate the total if the user uses the F7 or F8 function keys to move 
     between rows.
     SET VAR vkey = (LASTKEY(0))
     IF vkey = '[F7]' OR vkey = '[F8]' THEN
     There are additional example throughout this issue of the Exchange showing 
     how to trap for keystrokes in an EEP. 
     The EEP placed On exit from a row in the Table settings for the Transdetail 
     table accumulates the total in a variable. The variable that is accumulating 
     the sum needs to be cleared after the data is saved, before a new row is 
     added. Add the following command to the EEP used to clear the screen 
     location where the total is displayed, the EEP placed On entry into a row 
     for table 1, transmaster, in the form. 
     SET VAR vsumprice = NULL
     This clears the accumulator variable after the data is added to the tables
     Using a field level EEP
     Another way of calculating a sum is to use the SELECT function SUM and 
     calculate it from the rows of data stored in the table. This is easy to do 
     now by using the new SAVEROW EEP command. As you leave the field, the row
     is saved and the sum calculated. Place the EEP On exit from field on the 
     last field in the row needed in order to calculate the total. 
     For example, place it on exit from the vprice field in the transdetail table 
     on tranform. The row may be saved before all the data for the row is entered 
     if this is not the last located field on the row. Also, The user can exit 
     the row before putting data in this field. 
     Using this method calculates a total for all matching rows in the table, 
     not just those displayed on the screen. If you have a situation where you 
     may enter detail records at different times, don't use this method. The 
     total displayed will not match the amounts entered on the screen.
     This technique needs a form expression to put the ID number into a variable 
     for use by the EEP. For example, vtransid = transid. The expression can be
     placed on the transmaster table or the transdetail table. 
     SELECT SUM(extprice) INTO vtotprice FROM transdetail +
       WHERE transid = .vtransid
     WRITE .vtotprice AT 22,40 WHITE ON RED
     Again, this method also uses the EEP to clear the screen location where the 
     total was displayed. This is a better method to use when editing data as it 
     retrieves the sum from the table rather than calculating it as data is 
     Both of these methods are designed for use with a form that is adding new 
     data to a table. The EEP evaluates totals as the rows are added to the 
     region. To display a total when editing data, add an EEP to the first 
     table in the form that executes On entry into a row. Calculate the sum of
     matching rows for the region using the SELECT function SUM and display it
     using the WRITE command. As you scroll through rows in the first table, 
     the total will display for the matching rows in the region. 
     The two methods presented here are not the only ways to display a running 
     total in your form. Use the ideas presented by these techniques to add a 
     solution to your application.