MySQL GROUP_CONCAT(DISTINCT ...) 忽略数据

Question

i am concatenating multiple rows and columns of a table storing postal addresses using GROUP_CONCAT .

My table looks like this (simplified):

id | street  | hNumber
-----------------------
1  | streetA | 1       
-----------------------
2  | streetB | 2      
-----------------------
3  | streetC | NULL    
-----------------------

In some cases i need to concatenate addresse which i am doing like this: GROUP_CONCAT(DISTINCT table.street, ' ', table.hNumber SEPARATOR ', ') as street

This for example would give me StreetA 1, StreetB 2 as a result which is just what i want. Sadly this method does not work for cases where for example the hNumber is empty, in those cases it just returns street as NULL . For rows in which the hNumber table cell is empty i would like to see it just skip over the empty field and return street as StreetA 1, StreetC .

I hope someone can point me in a direction to approach this problem the proper way.

Answer 1

MySQL skips any of those rows that contain a NULL value. The short answer is to anticipate a possible NULL value for a column and prepare for it. eg:

SELECT GROUP_CONCAT(DISTINCT `street`, ' ', IFNULL(`hNumber`,"") SEPARATOR ', ')

(create empty string, if hNumber is NULL)