我有一个XML片段，所以:AlabamaALMontgomery46619005241914December1819AlaskaAKJuneau6984736632681January1959DelawareDEDover88512224907December1787我想检索(例如)最古老州(即“多佛”)的首府。我已经设法做到这一点://STATES/STATE[DATEOFSTATEHOOD='7December1787']/CAPITAL/text()但不知道怎么说'DATEOFSTATEHOOD={theearliestDATEOFSTATEHOOD}'。谁能指出我正确的方向，好