在没有组concat的MySQL中将多行合并为一

Question

I have a table in MySQL in which I need to join multiple rows. The table look like this:

Order_ID  |  Item_ID  |  color
1           1           white
1           2           red
2           1           black
2           1           blue

I want to combine the rows according to their Order_ID which will yield a result that looks like this:

Order_ID  |  Item_1_ID  | Item_1_color  | Item_2_ID  | Item_2_color
1           1             white           2            red
2           1             black           1            blue

I know that there's a way to combine two rows into one by using group concat, but I want to do it so that each field remains separated, not joined as if using group concat.

I already tried using statement join too, something like this:

SELECT o.*, o1.* FROM order o INNER JOIN order o1 ON o.Order_ID = o1.Order_ID

But for a few cases the rows that I want to join is too much, exceeding the limit of 61 join in MySQL.

Any help would be appreciated, thanks.

---edit---

There was this other parameter called group which determined the number of items per order. The table looks like this:

Order_ID   |  group
 1           1
 2           1

So if the order belongs to the same group they will have the same number of columns, but between one group and another the number of columns may be different. And my query is per one group only, so there's no problem in the differences between number of columns.

Answer 1

Use GROUP BY order_id , this will group your results and give you the result set you have described.

EDIT:

According to what you try to accomplish, I'd recommend to you to read about database normalization. You do not seem to have a primary key in your table, do you? Your table structure honestly does not make any sense, you should store the orders in one seperate table, eg order_id, user_id, ... and then have one table like yours with the items per order and then query for all your orders the items which belong to this order.

You don't want to add same results all in one row, but read each row into an array and then loop through the array.