MySQL选择混合和最大年份

Question

Hi guys I am developing a php and mysql application. I want to select Min and Max from year. It should show correct year like below:

Min = 1998
Max = 2014

My table structure like below

Table: Students

year varchar(32)    utf8_unicode_ci 
-------------------------------
06-04-2012
02-05-2014
19-04-1999
05-05-2014
06-04-1998

I try to use MySql Min and Max but not working well.

SELECT MIN(`year`) AS Year FROM `Students`

SELECT Max(`year`) AS Year FROM `Students`

Please help me with this issue.

Answer 1

You should not store dates as strings. You should store them as dates.

But, because you have this format, you can use the right() function to get the year:

select min(right(year, 4)), max(right(year, 4))
from students;

If, for some unfathomable reason, you do have to store dates as strings, then use the ISO standard YYYY-MM-DD format.

If you want the minimum of the entire values as a date, then convert it to a date:

select min(str_to_date(year, '%d-%m-%Y')), max(str_to_date(year, '%d-%m-%Y'))
from students;

But, you should be storing the date using the proper data type in the first place.

Answer 2

使用YEAR()函数就像

SELECT MIN(YEAR(`year`)) AS Year FROM `Students`