为另一列中的每个值选择不同的列，然后分组为

Question

I am pretty new to mySQL and I have had a hard time over the past 2 days trying to get this to work. I do not know if the title is correct in relation on what I am trying to fix, but if it is not, please correct me.

Here is the deal:

I have 4 columns... id, number, package_id, and date.

id - Increments every time a new row is inserted
number - Just a 2 digit number
package_id - ID of package
date - date and time row was inserted

Here is what an example table looks like: ( I omitted the time from the date )

id         number        package_id        date
---        ------        ----------        ----
1          12            20                08-01-2013
2          12            21                08-01-2013
3          12            20                08-01-2013
4          45            20                08-02-2013
5          45            22                08-02-2013
6          45            22                08-03-2013
7          12            20                08-03-2013
8          70            25                08-03-2013
9          70            26                08-03-2013
10         70            25                08-03-2013

Not only am I trying to select distinct for number and group by date. I am also trying to make sure it does it for each unique value in the package_id column.

To better explain, this is what i want the output to be like when I SELECT *:

id         number        package_id        date
---        ------        ----------        ----
1          12            20                08-01-2013
2          12            21                08-01-2013
4          45            20                08-02-2013
5          45            22                08-02-2013
6          45            22                08-03-2013
7          12            20                08-03-2013
8          70            25                08-03-2013
9          70            26                08-03-2013

As you can see only row 3 and 10 did not get selected because of the same number and package_id together within the same day.

How can I accomplish this?

Answer 1

Is this what you are looking for:

SELECT MIN(id), number, package_id, date
FROM MyTable
GROUP by number, package_id, date

It certainly satisfies your expected result set.