问题描述
|
我有两个表,并希望基于表a的引用ID从表b中获取technology_tag:
select b.dbid,b.technology_tag
from tblConnect a,tblSites b
where a.Site_DBID = 2
and a.Related_Site_DBID = 1
and (b.dbid = a.bsc_tag_dbid or b.dbid = a.related_bsc_dbid or b.dbid = a.related_msc_dbid)
我想在这里基于第一次出现来排序返回的行(在where子句中)
1st- b.dbid = a.bsc_tag_dbid
2cnd- b.dbid = a.related_bsc_dbid
3rd- b.dbid = a.related_msc_dbid
有谁知道如何做到这一点?
解决方法
首先,执行联接时应切换为使用实际的JOIN子句。就是说,这个ORDER BY子句应该执行您想要的操作:
SELECT
B.dbid,B.technology_tag
FROM tblConnect A
INNER JOIN tblSites B ON
B.dbid IN (A.bsc_tag_dbid,A.related_bsc_dbid,A.related_msc_dbid)
WHERE
A.Site_DBID = 2 AND
A.Related_Site_DBID = 1
ORDER BY
CASE
WHEN B.dbid = A.bsc_tag_dbid THEN 1
WHEN B.dbid = A.related_bsc_dbid THEN 2
WHEN B.dbid = A.related_msc_dbid THEN 3
ELSE 4 -- Not really necessary,but I always use an ELSE when I use CASE
END