重複したレコードの抽出、複数カラム結合[postgressql]
||で文字列結合するselect c_email || c_email_url from customertbl group by c_email || c_email_url having count(c_email || c_email_url) > 1重複しているレコードを全て抽出、処理遅いver
select * from customertbl where c_email || c_email_url in (select c_email || c_email_url from customertbl group by c_email || c_email_url having count(c_email || c_email_url) > 1)
