Question

我有一个表有许多类别，然后是一个反对这些值的值 - 我需要尝试从该表中提取（仅使用MySQL）值不为零的类别的名称和值本身

例如：

awk -F, '{print gsub("\"","\"\"",$2)}' OFS=, vehicle_file.txt

在上面我需要得到类似的东西：

ID   car   phone   gym   pension
1    200   15      12    20
2    0     15      12    25
3    0     0       0     30
4    0     0       0     0
5    150   20      12    0

以下查询返回正确的ID和值，但它也返回零值（ID 4除外），而不是类别名称：

1 Car     200
1 Phone   15
1 Gym     12
1 Pension 20
2 Phone   15
2 Gym     12
2 Pension 25
3 Pension 30
5 Car     150
5 Phone   20
5 Gym     12

我可以在PHP中执行此操作但是可以在MySQL中执行此操作吗？

Answer 1

您可以使用UNION ALL执行此操作：

SELECT id, car AS col
FROM benefits
WHERE car!=0

UNION ALL

SELECT id, phone AS col
FROM benefits
WHERE phone!=0

UNION ALL

SELECT id, gym AS col
FROM benefits
WHERE gym!=0

UNION ALL

SELECT id, pension AS col
FROM benefits
WHERE pension !=0

Answer 2

我认为实现此目标的最简单方法是使用UNION ALL，每列一次：

SELECT id,'Car' as val , car
FROM benefits WHERE car <> 0

UNION ALL

SELECT id,'Phone' as val , phone
FROM benefits WHERE phone <> 0

UNION ALL

SELECT id,'Car' as val , car
FROM benefits WHERE car <> 0

UNION ALL

SELECT id,'Gym' as val , Gym
FROM benefits WHERE Gym<> 0

UNION ALL

SELECT id,'Pension' as val , Pension 
FROM benefits WHERE Pension <> 0

order by id

在值不为零的查询中从MySQL获取字段名称

2 个答案: