对指定字段编号的字段求和
例如对字段编号为5的字段求和，就是写一个类似sum field(5)的合法语句。
程序代码：CREATE CURSOR tt (f1 I,f2 I)
FOR i=1 TO 100
INSERT INTO tt VALUES (i,2*i)
ENDFOR
n = 0
FOR i=1 TO FCOUNT()
cmd = "SUM "+FIELD(i)+ " TO n"
EXECSCRIPT(cmd)
? "sum "+FIELD(i)+" = "+TRANSFORM(n)
ENDFOR