Dear Monks

I'm facing the following problem: I need to convert the SQL query 
SELECT f1 AS x1,f2,f3,f4 as x2, (f4= f5) as x3 FROM %t"

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into 
SELECT x1, f2, f3, x2, x3 FROM ( SELECT f1 AS x1,f2,f3,f4 as x2, (f4= 
+f5) as x3 FROM Some_table_2006) UNION (SELECT f1 AS x1,f2,f3,f4 as x2
+, (f4= f5) as x3 FROM Some_tabel_2007)) As Tbl1 ;

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I need to make 1 big query because I don't want to merge the result of N tables together myself(the WHERE part can get complicated)
So my problem is now to convert 
SELECT f1 AS x1,f2,f3,f4 as x2, (f4= f5) as x3 FROM

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into 
SELECT x1,f2,f3,x2, x3 FROM

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To simplify the problem I started with 
SELECT f1,f2,f3,f4 as x2, (f4= f5) as x3 FROM

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It turns out that even this exercise is too hard for me. This is what I have so far 
use strict;
use warnings;

my $s = "SELECT f1,f2,f3,f4 as x2, (f4= f5) as x3 FROM ...." ;

$s =~ s/,\s*.*?\s+as/,/gi ;

print "OUT: $s\n";

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Gives 
OUT: SELECT f1, x2, x3 FROM ....

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All suggestions are welcome! or if there are better ways to do this I'm very interested!!

Thnx a lot
LuCa

In reply to regex needed to remove parts of SQL by jeanluca

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