Can I concatenate multiple MySQL rows into one fie

Question

Using MySQL, I can do something like:

SELECT hobbies FROM peoples_hobbies WHERE person_id = 5;

My Output:

shopping
fishing
coding

but instead I just want 1 row, 1 col:

Expected Output:

shopping, fishing, coding

The reason is that I'm selecting multiple values from multiple tables, and after all the joins I've got a lot more rows than I'd like.

I've looked for a function on MySQL Doc and it doesn't look like the CONCAT or CONCAT_WS functions accept result sets, so does anyone here know how to do this?

Answer 1

In my case I had a row of Ids, and it was neccessary to cast it to char, otherwise, the result was encoded into binary format :

SELECT CAST(GROUP_CONCAT(field SEPARATOR ',') AS CHAR) FROM table

Answer 2

Try this:

DECLARE @Hobbies NVARCHAR(200) = ' '

SELECT @Hobbies = @Hobbies + hobbies + ',' FROM peoples_hobbies WHERE person_id = 5;

Answer 3

I had a more complicated query, and found that I had to use GROUP_CONCAT in an outer query to get it to work:

Original Query:

SELECT DISTINCT userID 
FROM event GROUP BY userID 
HAVING count(distinct(cohort))=2);

Imploded:

SELECT GROUP_CONCAT(sub.userID SEPARATOR ', ') 
FROM (SELECT DISTINCT userID FROM event 
GROUP BY userID HAVING count(distinct(cohort))=2) as sub;

Hope this might help someone.

Answer 4

Use MySQL(5.6.13) session variable and assignment operator like the following

SELECT @logmsg := CONCAT_ws(',',@logmsg,items) FROM temp_SplitFields a;

then you can get

test1,test11