在 Oracle SQL 中连接 CASE
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CONCATENATE a CASE in Oracle SQL
提问by Cheddar Smith
I need to run a CASEexpression on a number of columns, the columns are Boolean, so if it's 0 I need to populate the column with the column name and if it's 1, I ignore the column/value. I then need to concatenate all these columns into one. Is it possible to do this in Oracle SQL?
我需要CASE在多列上运行一个表达式，这些列是布尔值，所以如果它是 0，我需要用列名填充列，如果它是 1，我会忽略列/值。然后我需要将所有这些列连接成一个。是否可以在 Oracle SQL 中执行此操作？
I've tried this:
我试过这个：
Select
||CASE
WHEN COL_A = 0 THEN 'COL_A'
ELSE ''
END||','
||CASE
WHEN COL_B = 0 THEN 'COL_B'
ELSE ''
END||
from ABC.123
Can this even been done? If not this way are there any other ways?
这甚至可以做到吗？如果不是这种方式还有其他方式吗？
回答by DCookie
Yes, it will work (if you clean up the syntax). Here's a simple example:
是的，它会起作用（如果您清理语法）。这是一个简单的例子：
with q as (
select 0 col_a, 1 col_b, 'Rec 1' id from dual
union all
select 1, 0, 'Rec 2' from dual
union all
select 0, 0, 'Rec 3' from dual
)
Select id,
CASE
WHEN COL_A = 0 THEN 'COL_A'
ELSE ''
END||','
||CASE
WHEN COL_B = 0 THEN 'COL_B'
ELSE ''
END "TheString"
from q
Result:
结果：
ID TheString
------- -------------------
Rec 1 COL_A,
Rec 2 ,COL_B
Rec 3 COL_A,COL_B
