查询的科目的格式为：科目编码.部门编码.个人编码.客户编码.供应商编码.项目编码
km="22310108.0101.0068.0088.hcjs.hchy"
如何转换成dm="22310108" and bmbm=="0101" and grbm=="0068" and khbm=="0088" and gybm=="hcjs" and xmbm=="hchy"
再比如km="286801.0108..yxgs"   
转换成  dm="286801" and bmbm=="0108" and khbm=="yxgs"
再比如km="286801"   则只转换成  dm="286801"

先将字符串分解，子字符串内容保存在数组中。
km="22310108.0101.0068.0088.hcjs.hchy"
ALINES(ASTR,CHRTRAN(KM,".",CHR(13)+CHR(10)))
LIST MEMORY LIKE ASTR
再在表达式相应的位置替换为数组中的内容

km = "22310108.0101.0068.0088.hcjs.hchy"
cExp = ""
ALINES(aExp, [dm="," and bmbm=="," and grbm=="," and khbm=="," and gybm=="," and xmbm=="], ",")
FOR i = 1 TO ALINES(aKM, km, ".")
    cExp = cExp + aExp[i] + aKM[i]
ENDFOR
cExp = cExp + ["]
? cExp

*km="22310108.0101.0068.0088.hcjs.hchy"
km="286801.0108..yxgs"   
*km="286801"
km=km+'.'
c2=''
FOR i1=1 TO ALINES(field_name, 'dm,bmbm,grbm,khbm,gybm,xmbm', ',')
    i2=AT('.',km)
    IF i2>0
        c1=ALLTRIM(LEFT(km,i2-1))
        IF NOT EMPTY(c1)
            c2=c2+"ALLTRIM("+field_name[i1]+")=='"+c1+"' and "
        ENDIF
        km=ALLTRIM(SUBSTR(km,i2+1))
    ENDIF
    IF EMPTY(km)
        EXIT
    ENDIF
ENDFOR
IF NOT EMPTY(c2)
    c2=LEFT(c2,LEN(c2)-4)
ENDIF
WAIT WINDOW c2

代码要兼容VFP6版本

完善一下
km="2231058508.gcb1...hcjs.hchy"
cExp=""
ALINES(aExp,[dm="," and bmbm=="," and grbm=="," and khbm=="," and gybm=="," and xmbm=="], ",")
FOR i=1 TO ALINES(aKM,km,".")
IF LEN(ALLTRIM(aKM[i]))>0
  cExp=cExp+aExp[i]+aKM[i]
ENDIF
ENDFOR
cExp=cExp+["]
?cExp

谢谢各位版主，你们的答案都很精彩！

km="2231058508.gcb1...hcjs.hchy"
IF LEN(KM)=0
    RETURN
ENDIF

下面的代码仍用三楼的代码
cExp = ""
ALINES(aExp, [dm="," and bmbm=="," and grbm=="," and khbm=="," and gybm=="," and xmbm=="], ",")
FOR i = 1 TO ALINES(aKM, km, ".")
    cExp = cExp + aExp[i] + aKM[i]
ENDFOR
cExp = cExp + ["]
? cExp

[ 本帖最后由 sdta 于 2015-5-14 15:05 编辑 ]

是不是把简单问题复杂化了，事先为什么要将查询条件拼接成一个字符串呢。