我正在为我的一个朋友开发一个小型艺术画廊网站,出于各种原因决定使用 PostgreSQL。到目前为止,一切都运行良好,但我遇到了一个小障碍。问题在于以下功能。
我的viewcount
专栏有歧义问题。冲突发生在更新语句和返回表之间。viewcount
除了将返回的表列更改为类似视图或创建另一个函数来更新计数之外,我不太确定如何解决此问题。
我对 SQL 的基本知识来自我使用 MSSQL 的工作。
create or replace function submission_getone
(
int -- submissionid
,boolean -- upcount
,int -- mmask
,int -- statemask
)
returns table
(
submissionid int
,galleryid int
,gallerytitle varchar(100)
,createdby int
,createdbyname varchar(32)
,alteredby int
,alteredbyname varchar(32)
,createdon timestamp
,alteredon timestamp
,title varchar(100)
,content text
,file1 varchar(64)
,viewcount int
,mlevel int
,typecode int
,statecode int
)
as
$$
declare
_submissionid alias for $1;
_upcount alias for $2;
_mmask alias for $3;
_statemask alias for $4;
begin
-- because the member may not want to see specific content (mmask)
-- and because the submitter my have not published the content (statemask),
-- include mmask and statemask in the where clause
-- referenced this for aliases in an update
-- http://stackoverflow.com/questions/11369757/postgres-wont-accept-table-alias-before-column-name
if _upcount = true then
update submission us set
viewcount = viewcount + 1
where us.submissionid = _submissionid
and (us.mlevel & _mmask) = us.mlevel
and (us.statecode & _statemask) = us.statecode;
end if;
return query
select
s1.submissionid
,s1.galleryid
,coalesce(g1.title, 'Orphan')::varchar(100) as gallerytitle
,s1.createdby
,m1.accountname
,s1.alteredby
,m2.accountname
,s1.createdon
,s1.alteredon
,s1.title
,s1.content
,s1.file1
,s1.viewcount
,s1.mlevel
,s1.typecode
,s1.statecode
from submission s1
left join gallery g1 on s1.galleryid = g1.galleryid
join member m1 on s1.createdby = m1.memberid
join member m2 on s1.alteredby = m2.memberid
where s1.submissionid = _submissionid
and (s1.mlevel & _mmask) = s1.mlevel
and (s1.statecode & _statemask) = s1.statecode;
end;
$$
language plpgsql;