如何在具有多个值的字段上对MySQL表排序

Question

I am stuck with a MySQL table created by another developer. Its a holiday cruise table with fields like destinations, ships and sailing dates (among other fields).

Destinations   Ships      Sailing Dates

Antarctica     MS QE2     2 Dec 2018, 1 Jan 2019

Antarctica     MS TBS     2 Feb 2019, 3 Mar 2019

Antarctica     MS JRB     9 Nov 2018, 5 Dec 2018

As indicated, each ship can have multiple sailing dates, entered as comma separated text. But I am interested only in the first sailing date of each row.

For example, "2 Dec 2018" is the first date on row one. Likewise, "2 Feb 2019" is the first date on row two, and so on.

I need a PHP SELECT statement to sort this entire table on the first dates of each row. To make things simpler, I thought of adding another date field to the table, and copy the first dates of each row onto that new date field, and then sort the table based on that field. But that is a round-about solution, which I don't prefer.

Is there a simple PHP/SQL statement which can achieve this? I thought of the PHP Explode() function. But I am not sure how I can incorporate that into a SELECT statement. Any help would be highly appreciated.

Update: Thanks for your suggestions. I totally agree, this table is a mess. Let's say I move the dates to a new table, with multiple rows for each row in the old table, like the following.

Destinations   Ships      Voyage ID

Antarctica     MS QE2     1

Antarctica     MS TBS     2

Antarctica     MS JRB     3

Dates Table

--Voyage ID------Sailing Dates

-------1------------2 Dec 2018

-------1------------1 Jan 2019

-------2------------2 Feb 2019

-------2------------3 Mar 2019

-------3------------9 Nov 2018

-------3------------5 Dec 2018

Now, what SQL command should I use to sort the old table by the first dates of each Voyage ID in the new DATES table.

Answer 1

You are suffering from a horrible database design. Instead of having one table for the ships, one for destinations, and one for actual trips, you have just one table. This is not what a relational database is supposed to be.

Moreover dates are not stored as dates but as strings and there are even multiple dates in one string. It can hardly be worse. So the best advice is to re-write the whole database.

If you don't want to re-design the database or if you are not allowed to, then my advice is: Do not try to tackle this in a SQL query. Simply read all records from the database instead and then do the string manipulation and sorting in PHP.