vf中如何设计密码登陆界面进入系统?

a=alltrim(thisform.text1.value)
if a="abcd"
do 开始
else
? "密码错误"
endif

sele passwordinfo &&检索用户密码表
if allt(thisform.text1.value)=""
thisform.text1.setfocus
else
if allt(thisform.text2.value)=""
thisform.text2.setfocus
else
locate for allt(用户名)=allt(thisform.text1.value);
.and.allt(密码)=allt(thisform.text2.value)
if eof()
messagebox("用户名或密码错误，请重新输入！",64,"提示")
thisform.text1.value=""
thisform.text2.value=""
thisform.text1.setfocus()
else
cyonghu=allt(thisform.text1.value)
cmima=allt(thisform.text2.value)
do menu.mpr
thisform.release
endif
endif
endif