php mySQL group concat 和 group by

Question

I have two table

table 1: 
 row  | car_id | car_model | 
  1      1          CAR 1      
  2      2          CAR 2      
  3      3          CAR 3  
  4      4          CAR 4

table 2:

 row  | car_id |  car_features |
  1      1          Features 1
  2      2          Features 2
  3      2          Features 3

What I want to display :

 row  | car_id | car_model | car_features |
  1      1          CAR 1      Features 1
  2      2          CAR 2      Features 2,Features 3
  3      3          CAR 3      
  4      4          CAR 4      

if I using group concat with group by

there will display row 1,2 and I want to display all the rows...

     row  | car_id | car_model | car_features |
      1      1          CAR 1      Features 1
      2      2          CAR 2      Features 2,Features 3

Please send me the sql statement..THANK!!

this is my query

$format = mysql_query("SELECT c.* , p.*, d.*,f.* ,GROUP_CONCAT(DISTINCT e.features_title SEPARATOR '<br>') AS 'car_features' FROM bsi_car_master c,bsi_car_type p, bsi_car_vendor d, bsi_selected_features f, bsi_car_features e WHERE c.car_type_id=p.id AND c.car_vendor_id=d.id AND c.car_id = f.car_id AND f.features_id = e.id GROUP BY c.car_id");

Answer 1

You should use an left join as suggested in the comments:

SELECT * FROM table1 LEFT OUTER JOIN table2 ON table1.car_id=table2.car_id;

Take a look at some MySQL tutorials. w3schools.org helped me a lot.

I guess that should do the trick for you.

But as said, please put a little more effort in your questions. I am glad to help, StackOverflow is not a free code service!

Answer 2

Use an outer join, so as to get rows even when no matching record in table2 exists.

UPDATE: Now that you have showed your query:

It is very strange to see your query, because on one hand you seem to be a beginner, on the other you are using a join syntax that was taught last century and is long since out-dated.

So your query should better look like this:

SELECT 
  c.*, 
  p.*, 
  d.*,
  f.*,
  GROUP_CONCAT(DISTINCT e.features_title SEPARATOR '<br>') AS car_features 
FROM bsi_car_master c
INNER JOIN bsi_car_type p ON p.id = c.car_type_id
INNER JOIN bsi_car_vendor d ON d.id = c.car_vendor_id
LEFT JOIN bsi_selected_features f ON f.car_id = c.car_id
LEFT JOIN bsi_car_features e ON e.id = f.features_id
GROUP BY c.car_id

p and d are inner-joined, ie there must be a match in p and d otherwise the c record is not selected. But f is outer-joined, so you get c (and p and d) even when no record in f exists for that c (then all f columns are null in that record). As to selecting e, we must also outer-join this, because again, if we got no match, we still want the record c with p and d.

I changed 'car_features' to car_features by the way. Single quotes are for string literals. Double quotes are for names, but they are not needed here