SQL查询在特定日期无效

Question

I have a weird problem in mysql! my query is

SELECT * FROM aa WHERE problemTime>= '2016/03/20' AND problemTime<= '2016/04/20' 

the result of this query is nothing , but when I change the first time to 2016/03/19 or 2016/03/21 I have the following result! I mean these queries

SELECT * FROM aa WHERE problemTime>= '2016/03/21' AND problemTime<= '2016/04/20' 

or

SELECT * FROM aa WHERE problemTime>= '2016/03/19' AND problemTime<= '2016/04/20' 

the result in both time ( 19th and 21th) is

but when I use 20th the result is noting

my main table is

I change the format of time from 2016/03/20 to 2016-03-20 ( I mean change / to - ) but it doesn't have change too!

whats the problem?

Answer 1

You should really be running a query like this if your problemTime column is datetime type:

SELECT * FROM aa 
WHERE    
  problemTime>= str_to_date('2016/03/20', '%Y/%m/%d') AND 
  problemTime <= str_to_date('2016/04/20', '%Y/%m/%d')

Don't rely on implicit conversions between string and date.. leave your table data alone and ensure you explicitly convert your where clause parameters to the same data type as in the table. Also remember that a date "without" a time is actually midnight on the day in question, and midnight is like zero, it's the first thing that happens on any given day. A time of 6am on a given date, is after midnight, so a query that asks for dates less than or equal to midnight on a particular date means the 6am date will be excluded

This is general good DB practice; do not convert table data where possible, because it can cause huge performance hits and wrong results

Answer 2

Your column "problemTime" have date with time. Do not convert table data, change your where clause (add time).

SELECT * FROM aa WHERE problemTime>= '2016/03/20 00:00:00' AND problemTime<= '2016/04/20 23:59:59'

Answer 3

Try this as per SQl Server.

 SELECT * FROM aa 
 WHERe  cast(problemTime AS date)  between  '2016/03/21' AND '2016/04/20'