Question

I have a table like this

records            
columnA columnB columnC columnD
gary    2011    0       a
gary    2011    0       b
gary    2010    1       a
mary    2011    0       a
mary    2010    1       b
mary    2010    1       c

i want to parse the table and if i find multiple lines where columnA columnB columnC are common to display the values from these three columns once followed by values found on columnD from each records where those columns A B C where the same.

Something like this

print output           
gary    2011    0   a,b
gary    2010    1   a
mary    2011    0   a
mary    2010    1   b,c

I am using mysql, I tried with distinct but it duplicates the prints when found similar A B C columns. for example instead of displaying

gary   2011    0   a,b

once, it will disaply this line twice and so on three, four … times, for each similar lines found…

Thank you,
Mozley

Answer 1

You’re looking for GROUP_CONCAT:

SELECT columnA, columnB, columnC,
     GROUP_CONCAT(DISTINCT columnD
               ORDER BY columnD ASC SEPARATOR ', ') AS columnD
     FROM records
     GROUP BY columnA, columnB, columnC

Result

| COLUMNA | COLUMNB | COLUMNC | COLUMND |
-----------------------------------------
|    gary |    2010 |       1 |       a |
|    gary |    2011 |       0 |    a, b |
|    mary |    2010 |       1 |    b, c |
|    mary |    2011 |       0 |       a |

See the demo