[英]Selecting rows as columns in mysql through php
您好,我正在尝试成功选择行作为mysql中的列。
也许有人可以帮助我。
这是我的桌子的样子
+----------+----------------------------------------------------+----------+
| 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 |
我正在尝试使结果看起来像:
+----------+----------------------------------------------------+-------+-------+-------+-------+-------+-------+-------+-------+-------+--------+
| 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,我想将行代码分组到单独的列中
最大行代码将永远是10。这就是为什么我有Code1-Code10
这是我现在正在做的,并且没有用。
$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,使brand_id和brand_name更改后,num变量将恢复为0。
如您所见,它正在执行我想要的操作,但是一旦转到下一行,num变量将继续向上移动到下一列。 这样便可以添加下一行代码。 我假设我在某些地方需要if语句,但是我不知道该怎么做。
如果有人可以更新我的查询,以便这种情况发生,我将非常感激
感谢您的时间。
您正在谈论的是部分转置 ,PHP不会自动完成。 但是,您可以自己进行一些小的修改。
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()
获得不同的代码 :
$codes = explode(',', $row['codes']);
注意:我对您的基础表结构做了一些假设。 相应地调整查询。
select a.name,a.value,a.code,T.code from test1 as a INNER JOIN test1 as T on
a.name=T.name and a.value = T.value and a.code != T.code group by a.name;
尝试这个。 我假设您的品牌名称和品牌ID总是一样。 如果它们会有所不同,则会删除对品牌名称的检查。
这只是查询的概念。 你可以调整以获得更好的结果
编辑:如果您必须完全在MySQL中执行此操作,这不是很漂亮,但是...
SELECT
a.brand_id, a.brand_name, b.linecode AS code1, c.linecode AS code2, d.linecode AS code3, e.linecode AS code4, f.linecode AS code4 FROM test a
LEFT JOIN
test b ON b.brand_id = a.brand_id
LEFT JOIN
test c ON c.brand_id = b.brand_id AND b.linecode != c.linecode
LEFT JOIN
test d ON d.brand_id = c.brand_id AND d.linecode != c.linecode AND d.linecode != b.linecode
LEFT JOIN
test e ON e.brand_id = d.brand_id AND e.linecode != d.linecode AND e.linecode != c.linecode AND e.linecode != b.linecode
LEFT JOIN
test f ON f.brand_id = e.brand_id AND f.linecode != e.linecode AND f.linecode != d.linecode AND f.linecode != c.linecode AND f.linecode != b.linecode
GROUP BY
a.brand_id
ORDER BY
a.brand_id
重复LEFT JOIN,直到您有10个代码列。
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