SQL Query filter with custom field - sql

Question

Below code are use to detect if there exist userid=1 followerid=2 AND userid=2 followerid=1, then the custom column 'bool' will return TRUE.
However, somehow i can't get rid the extra row.
Any better suggestion or recommendations are appreciated. Thank you.
SELECT DISTINCT a.id, a.userid, a.followerid,
CASE WHEN b.userid=a.followerid AND b.followerid=a.userid
THEN 'TRUE' ELSE 'FALSE' END AS bool
FROM tableUserfollow AS a, tableUserfollow AS b
where a.userid=1
tableUserFollow:
id userid followerid
1 1 2
2 3 4
3 1 4
4 5 1
5 2 1
The output result should be:
1 1 2 TRUE
3 1 4 FALSE
instead of this:
1 1 2 FALSE
1 1 2 TRUE
3 1 4 FALSE

Answer 1

If you want to know if the reciprocal relationship is present, then I think the simplest way is using a correlated subquery, left join, or outer apply:
select uf.*, coalesce(flag, 'FALSE') as
from tableUserfollow uf outer apply
(select 'TRUE' as flag
from tableUserfollow uf2
where uf2.userId = uf.followerId and uf2.follwerId = uf.userId
) f;
The join would look like:
select uf.*,
(case when uf2.userId is null then 'FALSE' else 'TRUE' end)
from tableUserfollow uf left join
tableUserfollow uf2
on uf2.userId = uf.followerId and uf2.follwerId = uf.userId

Answer 2

DECLARE #sql AS nvarchar(MAX);
DECLARE #Search AS nvarchar(MAX);
DECLARE #AllFiels Varchar(max);
DECLARE #FixedField Varchar(max);
SET #FixedField=( SELECT
ISNULL(( STUFF(
(
SELECT ', '+(a.value) FROM vwCustomColumns a
WHERE a.Name IN (SELECT items FROM dbo.Split(CustomReports.ReportFixedFields,',') )
FOR XML path('')
)
, 1,1,'')) ,'cR.ContractID [Contract ID]') FixedField
FROM CustomReports WHERE CustomReportId=#CustomReportId )
SET #AllFiels=#FixedField;
SET #sql ='SELECT count(*) OVER() AS Maxcount ,'+#AllFiels+'
FROM vwRequestLatest cR
INNER JOIN MasterUsers ON MasterUsers.UsersId = cR.Addedby
LEFT OUTER JOIN RequestTemplate cte ON cte.ContractTemplateId=cR.RequestTemplateId
LEFT OUTER JOIN CountryMaster co ON co.CountryId=cR.CountryId
ORDER BY
';
IF (#SortColumn = '')
BEGIN
IF (#Direction = 0)
SET #sql =#sql + ' cR.RequestId ASC '
ELSE
SET #sql =#sql + ' cR.RequestId DESC '
END
ELSE IF (#SortColumn = 'Request ID')
BEGIN
IF (#Direction = 0)
SET #sql =#sql + ' cR.RequestId ASC '
ELSE
SET #sql =#sql + ' cR.RequestId DESC '
END
SET #sql =#sql +'OFFSET ( '+CONVERT(VARCHAR(100),#PageNo)+' - 1 ) * '+CONVERT(VARCHAR(100),#RecordsPerPage)+' ROWS FETCH NEXT '+CONVERT(VARCHAR(100),#RecordsPerPage)+' ROWS ONLY'
EXEC(#sql);