FORM.INIT()
USE mytable AGAIN SHARED IN 0
CURSORSETPROP("Buffering", 5, "mytable")

*--User key in data and press save button

SELECT mytable
LOCATE FOR cPrimary == lcMyPrimary
IF NOT FOUND()
    APPEND BLANK
    REPLACE cPRimary WITH lcMyPrimary
ENDIF

REPLACE field1 with var1 ;

*--Replace all fields

IF TABLEUPDATE(.T., .F., "mytable")
    MESSAGEBOX("Save OK")
ELSE
    AERROR(laError)
    DO CASE
    CASE laError[2] = 1884  && Uniqueness error
       TABLEREVERT(.T., "myable")
       MESSAGEBOX("your custom message!!")
    CASE ...
    ENDCASE
ENDIF