개발/mysql4 mysql - php explode SELECT SubString_Index(reference_code , ',' , 1) SELECT SubString_Index(reference_code , ',' , -1) 2021. 10. 8. [mysql] 문자열 합치기 1. CONCAT SELECT CONCAT('a', 'b', 'c'); => abc 2. CONCAT_WS SELECT CONCAT_WS(' ', 'a', 'b', 'c'); => a b c 2021. 9. 9. [Mysql] Group by 마지막(최신) 값만 조회 SELECT * FROM( SELECT * FROM #{테이블} WHERE (#{노출할필드}, #{최신필드}) in ( SELECT #{노출할필드}, max(#{최신필드}) as #{최신필드}from #{테이블} group by #{노출할필드} ) ORDER BY #{최신필드} desc ) t GROUP BY t.#{노출할필드} 2021. 7. 27. [mysql] 중복글 삭제 #{column2} , #{column3} : 중복 DELETE FROM #{table} WHERE #{column1} IN( SELECT #{column1} FROM (SELECT #{column1} FROM #{table} GROUP BY #{column2} , #{column3} HAVING COUNT(*) > 1) AS tmp ) 2021. 6. 24. 이전 1 다음