[英]SQL Query return extra column depending of condition
I want to make a query which will add a column depending of what condition is meet(I have tried with sequelize without obtaining the result that I wanted) therefore I want to try with plain SQL because It does not have as many limitations.我想进行一个查询,该查询将根据满足的条件添加一列(我尝试使用 sequelize 却没有获得我想要的结果)因此我想尝试使用普通的 SQL 因为它没有那么多限制。
EXAMPLE: SELECT * FROM db.messages WHERE user_id = userID OR $contacts.user_id$ = userID
示例: SELECT * FROM db.messages WHERE user_id = userID OR $contacts.user_id$ = userID
If the first condition is meet I want to add a column like:如果满足第一个条件,我想添加如下列:
SELECT *,'type' as 'Inbox' FROM db.messages
Second condition:第二个条件:
SELECT *,'type' as 'Send' FROM db.messages
I have not manage to implement it with a CASE...THEN
我还没有设法用CASE...THEN
I would appreciette any comment.我会欣赏任何评论。
SQL CASE STatement: SQL 案例说明:
SELECT *,
CASE
WHEN user_id = userID THEN 'Inbox'
WHEN $contacts.user_id$ = userID THEN 'Send'
ELSE NULL
END AS type
FROM db.messages;
The syntax for the case statement seems to be invalid, check the documentation . case 语句的语法似乎无效,请查看文档。 Instead of this:而不是这个:
select
case
when a = x then 'a' as result
when b = x then 'b' as result
else null
end as y
from table_name
Try this:尝试这个:
select
case
when a = x then 'a'
when b = x then 'b'
end as 'result'
from table_name
or even simpler:甚至更简单:
select
case x
when a then 'a'
when b then 'b'
end as 'result'
from table_name
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