mysql - Searching MySQL in multiple columns and find which column matches

Question

I need some advice on how to accomplish this. If I have a query like SELECT * FROM catalog WHERE record_id = $var OR form_id = $var;

What I want to do is to know which column matched. Was it the record or form?

Answer 1

也许是这样的：

select a,b,c, 1 from catalog where record_id = $var
union
select a,b,c, 2 from catalog where form_id = $var

然后 1 或 2 告诉你哪个是哪个。

Answer 2

SELECT *, 
CASE
    WHEN record_id = $var and form_id = $var THEN 'both'
    WHEN record_id = $var THEN 'record_id'
    WHEN form_id = $var   THEN 'form_id'
    ELSE 'none'     -- can't happen becouse of where clause
END CASE  as how_it_was
FROM catalog WHERE record_id = $var OR form_id = $var;

请注意 $var 上的 sql 注入

Answer 3

select *,
case when record_id = $var then 1 else 2 end as matches 
from table
where record_id = $var or form_id = $var