Question

I have two master tables CompanyMaster, ActivityMaster for a child table CompanyActivities

ActivityMaster

ACTIVITYID   ACTIVITYNAME
A1           testActivity
A2           someActivity
A3           otheractivity
A4           someotheractivity
A5           anyotheractivity

CompanyMaster

COMPANYID  COMPANYNAME
C1         testcompany
C2         ACompany
C3         MyCompany
C4         SomeCompany
C5         ZCompany
C6         Company123
C7         ComapnyABC

CompanyActivities – The COMPANYID in CompanyActivities is having a primarykey-foreighkey relation ship with COMPANYID in CompanyMaster (primary key table) and ACTIVITYID is having a primarykey-foreighkey relation ship with ACTIVITYID in ActivityMaster(primary key table)

COMPANYID   ACTIVITYID
C1          A1
C1          A3
C3          A1
C3          A2
C4          A5
C5          A1
C6          A3
C7          A3

I want to do write a query to get the following output where all the rows in ACTIVITYID column of the ActivityMaster table will be converted to columns

Output

Companies  A1   A2  A3  A4  A5
C1         Y    N   Y   N   N
C2         N    N   N   N   N
C3         Y    Y   N   N   N
C4         N    N   N   N   Y
C5         Y    N   N   N   N
C6         N    N   Y   N   N
C7         N    N   Y   N   N

The output table displays all the companies as rows in the first column and all the activities are shown as columns that start after the first column, if there is row that contains both ACTIVITYID and COMPANYID it will set to Y in output otherwise it would be set to N

eg- COMPANYID C1 is having an activity ACTIVITYID A1 in CompanyActivities table so the first row in the second column that comes just below A1 and in the right to C1 is set Y, whereas C1 and A2 are not having a row, so the third column in the first row is set to N

I am using C#.net and 4 for loops to achieve the output now which is talking a heavy toll on the performance of the application, So i would like to do this using a query, I have searched for pivot queries, but all the examples i found knows the column names before-hand, which i don’t i only get the names of the column names by querying the ActivityMaster.

Answer 1

create table #CompanyMaster (COMPANYID int, COMPANYNAME varchar(30))
create table #ActivityMaster (ACTIVITYID int, ACTIVITYNAME varchar(30))
create table #CompanyActivities (COMPANYID int, ACTIVITYID int)

insert into #CompanyMaster
    SELECT 1, 'Company A'
    union all
    SELECT 2, 'Company B'

insert into #ActivityMaster
    SELECT 101, 'Activity X'
    union all
    SELECT 102, 'Activity Y'    
    union all
    SELECT 103, 'Activity Z'    

insert into #CompanyActivities      
    select 1, 102
    union all
    select 2, 101

-- build activities column names
--case [Activity X] when 0 then ''N'' else ''Y'' end as [Activity X],
--case [Activity Y] when 0 then ''N'' else ''Y'' end as [Activity Y],
--case [Activity Z] when 0 then ''N'' else ''Y'' end as [Activity Z]
declare @activities nvarchar(max)
set @activities
   = (
    select 'case [' + ACTIVITYNAME + '] when 0 then ''N'' else ''Y'' end as [' + ACTIVITYNAME + '],' + char(10)
    from #ActivityMaster
    for xml path('')
   )
set @activities = substring(@activities, 0, len(@activities)-1)

declare @activities_for nvarchar(max)
-- build activities column names in for
--[Activity X], [Activity Y], [Activity Z]
set @activities_for
   = (
    select '[' + ACTIVITYNAME + '],' + char(10)
    from #ActivityMaster
    for xml path('')
   )
set @activities_for = substring(@activities_for, 0, len(@activities_for)-1)


declare @sql nvarchar(MAX) = N'
select COMPANYNAME,
    <activities>
From
    (select c.COMPANYNAME, a.ACTIVITYNAME,
        (case 
            when ca.ACTIVITYID is not null and ca.COMPANYID is not null then 1
            else 0
        end) as STATUS
    from #CompanyMaster c
    cross join #ActivityMaster a
    left join #CompanyActivities ca on ca.COMPANYID = c.COMPANYID and a.ACTIVITYID = ca.ACTIVITYID)  p
pivot
    (
        sum(STATUS) for ACTIVITYNAME IN (<activities_for>)
    ) as pvt
'


set @sql = replace(@sql, '<activities>', @activities)
set @sql = replace(@sql, '<activities_for>', @activities_for)

print @sql
exec sp_executesql @sql

drop table #CompanyMaster
drop table #ActivityMaster
drop table #CompanyActivities