This is exactly what I was looking for. Unfortunately it doesn't work though. It always shows the second template, the one defined in 20=COA ...

I got it to work. Found this on another site:
styles.content.get = CONTENT
styles.content.get {
table = tt_content
select.orderBy = sorting
select.where = colPos=0
select.languageField = sys_language_uid
}

styles.content.getLeft < styles.content.get
styles.content.getLeft.select.where = colPos=1

styles.content.getRight < styles.content.get
styles.content.getRight.select.where = colPos=2

styles.content.getBorder < styles.content.get
styles.content.getBorder.select.where = colPos=3

I had to add this manually to the Typoscript and then it worked.

If you also use css_styled_content (CSC) then you shouldn't need to use the second post by Igor.

Using CSC will have previously defined what each of the styles.content.get are.

If you use automaketemplate:

temp.resource = COA
temp.resource {
10 = COA
10 {
if.isTrue.numRows < styles.content.getRight
10 = TEMPLATE
10 {

template = FILE
template.file = fileadmin/tmpl/tmpl01.html
}
}
20 = COA
20 {
if.isFalse.numRows < styles.content.getRight
10 = TEMPLATE
10 {

template = FILE
template.file = fileadmin/tmpl/tmpl02.html
}
}
}

### Configuration of the auto template parser: ###
plugin.tx_automaketemplate_pi1 {
content < temp.resource

Beware of double-using the same if option. E.g. what I had was:

ifTrue.numRows < styles.content.getLeft
ifTrue.numRows < styles.content.getRight

and it ignores the first row. That's probably the expected behaviour but strange for a newbie like me.

The workaround was to use:

value = 0
ifGreaterThan.numRows < styles.content.getLeft
ifTrue.numRows < styles.content.getRight

(or .equals instead of repeated isFalse)

Please help me with such a problem

I need to load CSS file according to different conditions

(if left and normal columns are not empty)
(if right and normal columns are not empty)
(if left and right and normal columns are not empty)

is it possible to make such complex conditions using typoscript?

This Typoscript template wraps "normal" coloumn in different CSS ID:s depending on if there is content in Left and Right. There are four alternatives:
- Only normal coluomn
- Left and Normal
- Right and normal
- Left, Normal and Right

Normal coloumn resizes to fit in the area. CSS futher down.

lib.contentMain= COA
lib.contentMain{

# Wraps maincontent in CSS style "main_alt1" if there is content in Right but not in Left
10 = COA
10.wrap = <div id="main_alt1"> | </div>
10 {
if.isTrue.numRows < styles.content.getLeft
if.isFalse.numRows < styles.content.getRight
10 = CONTENT
10 < styles.content.get
}

# Wraps maincontent in CSS style "main_alt2" if there is content in Left but not in Right
20 = COA
20.wrap = <div id ="main_alt2"> | </div>
20 {
if.isTrue.numRows < styles.content.getRight
if.isFalse.numRows < styles.content.getLeft
10 = CONTENT
10 < styles.content.get
}

# Wraps maincontent in CSS style "main_alt3" if there is NO content in Right or Left.
30 = COA
30 {
if.isFalse.numRows < styles.content.getLeft
10 = COA
10.wrap = <div id="main_alt3"> | </div>
10 {
if.isFalse.numRows < styles.content.getRight
10 = CONTENT
10 < styles.content.get
}
}

# Wraps maincontent in CSS style "main_alt4" if there IS content in Right and Left.
40 = COA
40 {
if.isTrue.numRows < styles.content.getLeft
10 = COA
10.wrap = <div id="main_alt4"> | </div>
10 {
if.isTrue.numRows < styles.content.getRight
10 = CONTENT
10 < styles.content.get
}
}
}

Everything is wraped inside a div id="content" with a fixed width so the other content can float relative to it.

#content{
position: relative;
width: 900px;
margin-left: auto;
margin-right: auto;
}

#main_alt1{
width: 700px;
float: right;
}

#main_alt2{
width: 700px;
float: left;
}
#main_alt3{
clear: both;
}
#main_alt4{
width: 520px;
float: left;
margin-left: 6px;
}

#left{
float: left;
width: 180px;
}

#right{
float: right;
width: 180px;
}

#border{
border: 1px solid #444;
position: absolute;
top: 0px;
right: 0px;
}