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Alternative sans-regex solution... Input (test.txt) Large toolbox (metal) for sale (hammer is required) serious inquiries only. All employees are required to attend. Meeting scheduled for Tuesday (Formal attire required) otherwise call (or email) us. Code $data = file('test.txt', FILE_IGNORE_NEW_LINES|FILE_SKIP_EMPTY_LINES); foreach ($data as $line) { if ($p = parens_and_req($line)) { $line = str_replace($p, "<span style='color:red;'>$p</span>", $line ); } echo "<p>$line</p>"; } function parens_and_req($str) { $k = strlen($str); $p2 = 0; while (( $p1 = strpos($str, '(', $p2)) !== false ) { $p2 = strpos($str, ')', $p1); if ($p2 === false) { $p2 = $k-1; } $parens = substr($str, $p1, $p2-$p1+1); if (strpos($parens, 'required') !== false) { return $parens; } } return false; } Output

Use DATE type columns for your dates, not varchar. Have your leaving dates either a valid date or NULL. SELECT eemp_id , fname , lname , AVG(timestampdiff(MONTH, joining_date, coalesce(leaving_date, curdate()))) as av_mths FROM employee_details ed JOIN employee e ON e.empid = ed.eemp_id GROUP BY eemp_id HAVING av_mths >= 36;