从mysql查询中提取特定日期

Question

I have to columns in my table (check_in and checkout). Both of them has this format dd-mm-yyyy. I want to check if there is any date available between my two paramaters(inputs).

I tried like this:

select * from rezervare where date(check_out) > date('my_checkout_input') 

but this works only in a few cases. If i have a reservation between 12-03-2015 - 15-03-2015 and another reservation between 17-03-2015 and 20-03-2015. It will not take the date between 16-03-2015 as a free date. Can you give me some ideas ?

Answer 1

create table rezervare (
    id int auto_increment,
    check_in varchar(10),
    checkout varchar(10),
    primary key (id)
);
insert into rezervare values
    (null, '12-03-2015', '12-03-2015'),
    (null, '13-03-2015', '13-03-2015'),
    (null, '14-03-2015', '14-03-2015'),
    (null, '15-03-2015', '15-03-2015'),
    (null, '16-03-2015', '16-03-2015'),
    (null, '17-03-2015', '17-03-2015'),
    (null, '19-03-2015', '19-03-2015'),
    (null, '20-03-2015', '20-03-2015')
;

select * from rezervare;
+----+------------+------------+
| id | check_in   | checkout   |
+----+------------+------------+
|  1 | 12-03-2015 | 12-03-2015 |
|  2 | 13-03-2015 | 13-03-2015 |
|  3 | 14-03-2015 | 14-03-2015 |
|  4 | 15-03-2015 | 15-03-2015 |
|  5 | 16-03-2015 | 16-03-2015 |
|  6 | 17-03-2015 | 17-03-2015 |
|  7 | 19-03-2015 | 19-03-2015 |
|  8 | 20-03-2015 | 20-03-2015 |
+----+------------+------------+

If your schema same as this, you can't use date function, because:

select id, date(check_in), date(checkout) from rezervare ;
+----+----------------+----------------+
| id | date(check_in) | date(checkout) |
+----+----------------+----------------+
|  1 | NULL           | NULL           |
|  2 | NULL           | NULL           |
|  3 | NULL           | NULL           |
|  4 | NULL           | NULL           |
|  5 | NULL           | NULL           |
|  6 | NULL           | NULL           |
|  7 | NULL           | NULL           |
|  8 | NULL           | NULL           |
+----+----------------+----------------+

But you can use between, in my example it works fine:

select * from rezervare where checkout between '12-03-2015' and '15-03-2015';
+----+------------+------------+
| id | check_in   | checkout   |
+----+------------+------------+
|  1 | 12-03-2015 | 12-03-2015 |
|  2 | 13-03-2015 | 13-03-2015 |
|  3 | 14-03-2015 | 14-03-2015 |
|  4 | 15-03-2015 | 15-03-2015 |
+----+------------+------------+

select * from rezervare where checkout > '14-03-2015';
+----+------------+------------+
| id | check_in   | checkout   |
+----+------------+------------+
|  4 | 15-03-2015 | 15-03-2015 |
|  5 | 16-03-2015 | 16-03-2015 |
|  6 | 17-03-2015 | 17-03-2015 |
|  7 | 19-03-2015 | 19-03-2015 |
|  8 | 20-03-2015 | 20-03-2015 |
+----+------------+------------+

But true way - alter table and use correct date type.