为什么MySQL选择日期在不同月份不起作用

Question

I have a very old database I made when I was still learning PHP and MySQL. If I populate:

SELECT * FROM Jobs WHERE (date BETWEEN 'Aug.01 2016' AND 'Aug.31 2016')

I can actually populate rows

Found rows: 4 Warnings: 0 Duration for 1 query: 0.000 sec.

But once I change my month (moving the range from Aug 1 to July 1):

SELECT * FROM Jobs WHERE (date BETWEEN 'Jul.01 2016' AND 'Aug.31 2016')

I got nothing even so the range July 1 ~ Aug 31 includes Aug 1 ~ Aug 31 (from previous example), which should populate at least 4 rows

Found rows: 0 Warnings: 0 Duration for 1 query: 0.016 sec.

Is there a way I can populate the rows even they have different month?

Answer 1

You need to first convert your date string to a valid date:

SET @date := 'Aug.01 2016';

SELECT STR_TO_DATE(@date,'%M.%d %Y');

Output(yyyy-mm-dd): 2016-08-01

Now use this in your query to search for result having dates between 2016-07-01 & 2016-08-31 .

SELECT 
*
FROM Jobs 
WHERE STR_TO_DATE(date,'%M.%d %Y') BETWEEN '2016-07-01' AND '2016-08-31';

Note: But date should be stored in a date datatype column. It's high time you converted the datatype to date of your date column.

In order to do that follow the steps below:

ALTER TABLE Jobs
ADD new_date_column date;

UPDATE Jobs 
SET new_date_column = STR_TO_DATE(date,'%M.%d %Y');

ALTER TABLE Jobs DROP COLUMN `date`;

ALTER TABLE Jobs CHANGE COLUMN `new_date_column` `date` date;

Steps in a nut shell:

1. Add a new column in Jobs table of type date .

2. Now update this new column with the values from your date column after converting to a valid date.

3. You don't need that date column. So drop it.

4. Now rename the newly created column to date .