您好,我正试图在mysql中成功地选择行作为列。
也许有人能帮我。
这是我桌子的样子
+----------+----------------------------------------------------+----------+
| brand_id | brand_name | linecode |
+----------+----------------------------------------------------+----------+
| DPQT | 1-800 Tow Truck | DER |
| DPQT | 1-800 Tow Truck | DCF |
| DPQT | 1-800 Tow Truck | DCA |
| DPQT | 1-800 Tow Truck | AAA |
| DPQT | 1-800 Tow Truck | DDD |
| BLGR | 1-800-Radiator | Curt |
| BGVM | 100+ Manufacturing/Coyote | ASC |
| DPQS | 10C Technologies Inc | AQW |
| DPQS | 10C Technologies Inc | ASQ |
| FDJG | 2 Cool AirVents | CAS |
我试着让结果看起来像:
+----------+----------------------------------------------------+-------+-------+-------+-------+-------+-------+-------+-------+-------+--------+
| brand_id | brand_name | Code1 | Code2 | Code3 | Code4 | Code5 | Code6 | Code7 | Code8 | Code9 | Code10 |
+----------+----------------------------------------------------+-------+-------+-------+-------+-------+-------+-------+-------+-------+--------+
| DPQT | 1-800 Tow Truck | DCF | DCA | AAA | DDD | DER | NULL | NULL | NULL | NULL | NULL |
| BLGR | 1-800-Radiator | Curt | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL |
| BGVM | 100+ Manufacturing/Coyote | ASC | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL |
| DPQS | 10C Technologies Inc | ASQ | AQW | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL |
| FDJG | 2 Cool AirVents | CAS | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL |
如您所见,当brand_id和brand_name相同时,我希望将行代码分组为单独的列
最大行代码是10。这就是为什么我有代码1-10
这就是我现在正在做的,它不起作用。
$sql0 = 'set @num := 0';
$result = mysqli_query($dbh,"select brand_id, brand_name,
max(case when group_row_number = 1 then linecode end) Code1,
max(case when group_row_number = 2 then linecode end) Code2,
max(case when group_row_number = 3 then linecode end) Code3,
max(case when group_row_number = 4 then linecode end) Code4,
max(case when group_row_number = 5 then linecode end) Code5,
max(case when group_row_number = 6 then linecode end) Code6,
max(case when group_row_number = 7 then linecode end) Code7,
max(case when group_row_number = 8 then linecode end) Code8,
max(case when group_row_number = 9 then linecode end) Code9,
max(case when group_row_number = 10 then linecode end) Code10
from ( select brand_id, brand_name, linecode, @num := @num + 1 as group_row_number from linecodes_temp ) src
group by brand_id, brand_name
order by if(linecode = '' or linecode is null,1,0), brand_name ASC");
我得到的结果是
+----------+----------------------------------------------------+-------+-------+-------+-------+-------+-------+-------+-------+-------+--------+
| brand_id | brand_name | Code1 | Code2 | Code3 | Code4 | Code5 | Code6 | Code7 | Code8 | Code9 | Code10 |
+----------+----------------------------------------------------+-------+-------+-------+-------+-------+-------+-------+-------+-------+--------+
| DPQT | 1-800 Tow Truck | DER | DCF | DCA | AAA | DDD | NULL | NULL | NULL | NULL | NULL |
| BLGR | 1-800-Radiator | NULL | NULL | NULL | NULL | NULL | Curt | NULL | NULL | NULL | NULL |
| BGVM | 100+ Manufacturing/Coyote | NULL | NULL | NULL | NULL | NULL | NULL | ASC | NULL | NULL | NULL |
| DPQS | 10C Technologies Inc | NULL | NULL | NULL | NULL | NULL | NULL | NULL | AQW | ASQ | NULL |
| FDJG | 2 Cool AirVents | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | CAS |
我需要一种方法,以便一旦brand_id和brand_name更改,num变量返回到0。
正如您所看到的,它正在做我希望它做的事情,但是一旦它转到下一行,num变量就会继续向上转到下一列。所以这就是下一行代码被添加的地方。我想我需要一个if语句,但是我不知道怎么做。
如果有人能更新我的查询以便发生这种情况,我将非常感谢
谢谢你抽出时间。
最佳答案
您所说的是部分转置,PHP并不是自动转置的。不过,你可以自己做一些小的修改。
在查询中,使用GROUP_CONCAT()
:
SELECT brand_id, brand_name, GROUP_CONCAT(linecode) AS codes brands GROUP BY brand_id, brand_name
在PHP中,使用
explode()
获取不同的代码:$codes = explode(',', $row['codes']);
注意:我对您的基本表结构做了一些假设。相应地调整查询。