The date format commonly used SQL query and duplicate data

     

      This article lists some of the work commonly used in SQL, to improve work efficiency.

1 Date format

     Use DATE_FORMAT (get_date, '% Y-% m-% d') function formatted. Wherein: get_date fields that need to be formatted, '% Y-% m-% d' is formatted date format. E.g:

select date_format('1997-10-04 22:23:00','%y %M %b %D %W %a %Y-%m-%d %H:%i:%s %r %T');
结果：97 October Oct 4th Saturday Sat 1997-10-04 22:23:00 10:23:00 PM 22:23:00

SELECT count(*) FROM house Where get_date like '2006%-07%';

 

2 query whether there are duplicate records specified field

SELECT house_id, count(id) AS sumCount
FROM house
GROUP BY house_id HAVING sumCount > 1;

     Here you can get all house_id have duplicate records, delete and update when we do these data processing such as the time, very easy.

3 Find more fields for duplicate records 

select *
from vitae a
where (a.peopleId,a.seq) in (select peopleId,seq from vitae
group by peopleId,seq having count(*) >
1)

 

 

 Continuously updated, the next issue is more exciting.