将多个MySQL行合并到一个字段中

Question

I tried a solution in a similar question here at stackoverflow, but with no success. Here is mysql query:

$sql= "SET group_concat_max_len = 2048";
$sql = "select p.id,p.name,p.logo,p.short_description,  GROUP_CONCAT(c.category_name SEPARATOR ', ')  from eshop p, eshop_cat c  GROUP BY p.id";

I can't understand what is wrong with the query, but the c.category is resulting empty. If i do this without group concat and use inner join i receive all the data right. But i have multiple rows for the same product for each category of every product. (ex if a product have 3 categories, then it shows the product 3 times.) I just want to have 1 row for every product and the categories together separated by comma Can you help me please

Answer 1

Try like this

$sql= "SET group_concat_max_len = 2048";
$sql = "select p.id,p.name,p.logo,p.short_description,  GROUP_CONCAT(c.category_name SEPARATOR ', ') as category_names   from eshop p join  eshop_cat c on
p.id=c.id GROUP BY p.id";

Just place your relational column p.id=c.id then it will work for you.