如何从表中使用where条件获得列名称

Question

当前我有一个cop_config表。我想要的是使用where条件获取一些（不是全部）列名。现在，我只能用下面的代码来获取所有的列名..

$cop_value = "SELECT COLUMN_NAME 
FROM INFORMATION_SCHEMA.COLUMNS 
WHERE TABLE_NAME = 'cop_config' and is_nullable = 'NO'"; 
     $cop_result = $conn->query($cop_value); 
     while($cop_row = $cop_result->fetch_assoc()){ 
     $cop_row = implode(',', $cop_row); 
     echo $cop_row; 
    } 

currenlty我的输出是：

iddevice_keyfirst_pulse1first_pulse2first_pulse3first_pulse4first_pulse5first_pulse6first_pulse7first_pulse8second_pulse1second_pulse2second_pulse3second_pulse4second_pulse5second_pulse6second_pulse7second_pulse8 

这里是表：

从表我想要的是根据device_key（在cop_config表中）只有那些有1个值的列名。我知道我的问题解释不太好，请看表格图片，以便更好地理解您的担忧。

像device_key YMR200，我只是想获得列名 - first_pulse1 & second_pulse2

与之相似的device_key VTA600我想获得列名 - first_pulse3 & second_pulse4。

------------------------------☺☻♀♥♣♦♣W ------ -------- ------------------------ 经过长时间的搜索和谷歌目前我使用

 $cop_value = "SELECT 'first_pulse1' from cop_config where first_pulse1 = 1 and device_key = 'VTA600' union 
select 'first_pulse2' from cop_config where first_pulse2 = 1 and device_key = 'VTA600' union 
select 'second_pulse1' from cop_config where second_pulse1 = 1 and device_key = 'VTA600' union 
select 'second_pulse2' from cop_config where second_pulse2 = 1 and device_key = 'VTA600'"; 


    $cop_result = $conn->query($cop_value); 
     while($cop_row = $cop_result->fetch_assoc()){ 

     echo $cop_row; 
    } 

我knwo我在这里作出错误的错误同时获取值...但我不知道如何从查询中获取值。 PLZ帮助 感谢..

Answer 1

尝试
对于SQL Server：

SELECT 
    sys.columns.name AS ColumnName 
FROM 
    sys.columns 
WHERE 
    sys.columns.name = 'first_pulse1' 
    and 
    exists(select top 1 * from cop_config where device_key = 'YMR200') 

对于Oracle： see this

PLSQL： see this

对于MySQL： see this

Answer 2

最后经过长时间的搜索，我发现这个解决方案和它的工作。但我不确定这是否是正确的做法。目前我正在使用union来根据需要获取数据。这里是代码

$cop_value = "SELECT 'first_pulse1' from cop_config t where first_pulse1 = 1 and device_key = 'YMR200' union 
select 'first_pulse2' from cop_config t where first_pulse2 = 1 and device_key = 'YMR200' union 
select 'first_pulse3' from cop_config t where first_pulse3 = 1 and device_key = 'YMR200' union 
select 'first_pulse4' from cop_config t where first_pulse4 = 1 and device_key = 'YMR200' union 
select 'first_pulse5' from cop_config t where first_pulse5 = 1 and device_key = 'YMR200' union 
select 'first_pulse6' from cop_config t where first_pulse6 = 1 and device_key = 'YMR200' union 
select 'first_pulse7' from cop_config t where first_pulse7 = 1 and device_key = 'YMR200' union 
select 'first_pulse8' from cop_config t where first_pulse8 = 1 and device_key = 'YMR200' union 
select 'second_pulse1' from cop_config t where second_pulse1 = 1 and device_key = 'YMR200' union 
select 'second_pulse2' from cop_config t where second_pulse2 = 1 and device_key = 'YMR200' union 
select 'second_pulse3' from cop_config t where second_pulse3 = 1 and device_key = 'YMR200' union 
select 'second_pulse4' from cop_config t where second_pulse4 = 1 and device_key = 'YMR200' union 
select 'second_pulse5' from cop_config t where second_pulse5 = 1 and device_key = 'YMR200' union 
select 'second_pulse6' from cop_config t where second_pulse6 = 1 and device_key = 'YMR200' union 
select 'second_pulse7' from cop_config t where second_pulse7 = 1 and device_key = 'YMR200' union 
select 'second_pulse8' from cop_config t where second_pulse8 = 1 and device_key = 'YMR200'"; 


     $cop_result = $conn->query($cop_value); 
     while($cop_row = $cop_result->fetch_assoc()){ 
     $cop_row = implode(',', $cop_row); 
     echo $cop_row; 
    } 

，这是device_key YMR200

first_pulse1second_pulse2