SQL::Statement is your friend. For example:

use SQL::Statement
my $parser = SQL::Parser->new();
$parser->{PrintError}=0;
$parser->{RaiseError}=1;
for my $sql(<DATA>) {
    my $stmt = SQL::Statement->new($sql,$parser);
    printf "Command      %s\n",$stmt->command;
    printf "Num Pholders %s\n",scalar $stmt->params;
    printf "Columns      %s\n", join',', map{$_->name} $stmt->columns;
    printf "Tables       %s\n",join',',$stmt->tables;
    printf "Where op     %s\n",join',',$stmt->where->op;
    printf "Order Cols   %s\n",join',',map{$_->column}$stmt->order;
}
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The module will handle implicit and explicit joins, column and table alias, complex nested where clauses, and more. It doesn't yet handle subqueries.