Use a variable in Typoscript "select" - select

Question

I try to get an author of a Typo3 site and after this i try to fill a Typo3 select (typoscript) with the resulting ID.
Its somehow working, but i can not use the lib oder variable as datasource of another select
I tryed to play arround with LOAD_REGISTER or marker. But i think it has to be a way to use a select result or another "lib" result in a select.
Here is my code:
// Returns succsessfully "neuz8" and i can use this in fluid
lib.author = TEXT
lib.author.data = page:author
lib.Authornavigation = CONTENT
lib.Authornavigation {
stdWrap.required = 1
table = be_users
select {
uidInList = 0
pidInList = root
selectFields = be_users.uid as id, be_users.realName as rn, be_users.profile_pid as prid
where = be_users.profile_pid != '0'
andWhere = be_users.realName={lib.author} // Is not working, why?
// I tryed: combinations of andWhere.data or lib.author.data,
// with and without {},
// with LOAD_REGISTER,
// with "markers",
//andWhere = be_users.realName='neuz8' < this works and returns "39", the correct ID
andWhere.wrap =
markers {
//author.data = {page:author}
}
}
renderObj = COA
renderObj {
10 = TEXT
10.field = prid
10.wrap2 = ###SPLITTER### |
}
stdWrap.split {
token = ###SPLITTER###
cObjNum = 1 |*| 2 |*| 1
1.current = 1
2.current = 1
2.wrap = |,
}
}

Answer 1

This should work
replace
// andWhere = be_users.realName={lib.author} // Is not working, why?
with
andWhere = be_users.realName=
andWhere.postCObject < temp.author

Answer 2

You can try select.markers:
page.60 = CONTENT
page.60 {
table = tt_content
select {
pidInList = 73
where = header != ###whatever###
orderBy = ###sortfield###
markers {
whatever.data = GP:first
sortfield.value = sor
sortfield.wrap = |ting
}
}
}
Docs » Functions » select (see part markers)