how to: refer to select list calculations other places in the calculations.

<div class="Section1"><p class="MsoNormal"><font face="Arial" size="2"><span style="font-size:10.0pt;
font-family:Arial">Hi,</span></font><p class="MsoNormal"><font face="Arial" size="2"><span style="font-size:10.0pt;
font-family:Arial">I have very complex sql (generated by cognos) I’m porting from Teradata that basically uses column
aliasin the calculated columns. </span></font><p class="MsoNormal"><font face="Arial" size="2"><span
style="font-size:10.0pt;
font-family:Arial">Is there any way to do this type of thing in Psql?</span></font><p class="MsoNormal"><font
face="Arial"size="2"><span style="font-size:10.0pt; 
font-family:Arial"> </span></font><p class="MsoNormal"><font face="Arial" size="2"><span style="font-size:10.0pt;
font-family:Arial">Essentially I need to do is refer to a calculated column later in the select list (but far more
complex– like 50 pages printed out)   </span></font><p class="MsoNormal"><font face="Arial" size="2"><span
style="font-size:10.0pt;
font-family:Arial">sel a,b,a+b as c, c*d, c*f, c*g, c*h, c*I, c*j, c*k,……       ---  where c is a calculated column
usedin other calculations.</span></font><p class="MsoNormal"><font face="Arial" size="2"><span style="font-size:10.0pt; 
font-family:Arial">from ....</span></font><p class="MsoNormal"><font face="Arial" size="2"><span
style="font-size:10.0pt;
font-family:Arial"> </span></font><p class="MsoNormal"><font face="Arial" size="2"><span style="font-size:10.0pt;
font-family:Arial"> </span></font><p class="MsoNormal"><strong><b><font face="Arial" size="2"><span style="font-size:
10.0pt;font-family:Arial">Doug Little</span></font></b></strong><p class="MsoNormal"><font face="Arial" size="2"><span
style="font-size:10.0pt;
font-family:Arial">Sr. Data Warehouse Architect | Enterprise Data Management | Orbitz Worldwide </span></font><p
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