Transforming Data From 2 Tables into 1 - sql

Question

I'm working with a database that allows the storage of "Custom Property" fields with each record in an "Item" table. This is done by having preset fields called [CustomString00] through [CustomString199], [CustomNumber00] through [CustomNumber199] and [CustomDate00] through [CustomDate199] in the Item table. There is another table called the "CustomProperty" table that assigns the name to each custom field and the column to use in the Item table. Here is how it looks.
Item:
| Id | CustomString00| ... | CustomString199 | CustomNumber00 | ... | CustomNumber199 | CustomDate00 | ... | CustomDate199 |
| 1 | 'IN REPAIR' | ... | NULL | 78.4 | ... | NULL | 2017-03-04 | ... | NULL |
| 2 | 'FINISHED' | ... | NULL | 68.5 | ... | NULL | 2017-03-05 | ... | NULL |
| 3 | 'WIP' | ... | NULL | NULL | ... | NULL | 2017-03-07 | ... | NULL |
CustomProperty:
| Name | Type| ColumnName |
| 'Status' | 0 | 'CustomString00' |
| 'Temperature' | 1 | 'CustomNumber00' |
| 'Made Date' | 2 | 'CustomDate00' |
For each Custom Property that is defined, there will be a record in the CustomProperty table that will indicate what data type it is and which column to use for that property. Currently, there could be up to 200 Custom Properties defined for each type, ie, 200 Text, 200 Date and 200 Numeric. The user defines the Custom Properties as they need them. If a user is only using 55 total custom properties, then a lot of the fields in the Item table will not be used.
I would like to create a view that is more 'friendly' so that our users can create their own reports to show these properties. This view would use these two tables to create a new table that looked like this:
| Id | Status | Temperature | Made Date |
| 1 | 'IN REPAIR' | 78.4 | 2017-03-04 |
| 2 | 'FINISHED' | 68.5 | 2017-03-05 |
| 3 | 'WIP' | NULL | 2017-03-07 |
This view should show a column for each property that is defined in the Custom Property table. For This example, there are only 3 Custom Properties defined, so 3 fields are shown in this view. If all 600 Custom Properties were defined, then there would be 600 fields in this view. If there is a value stored for that Custom Property in the Item table, then that value is shown. If there is no value then a NULL would be shown for that property (as shown in Temperature for Item 3).
Using Dynamic SQL I've got some results, but not what I'm looking for. I've made a query that Unpivots the Custom Property fields and returns a result of Items like this:
| Id | CPName | CPTextValue | CPNumberValue | CPDateValue |
| 1 | 'Status' | 'IN REPAIR' | NULL | NULL |
| 1 | 'Temperature' | NULL | 78.4 | NULL |
| 1 | 'Made Date' | NULL | NULL | 2017-03-04 |
| 2 | 'Status' | 'FINISHED ' | NULL | NULL |
| 2 | 'Temperature' | NULL | 68.5 | NULL |
| 2 | 'Made Date' | NULL | NULL | 2017-03-05 |
| 3 | 'Status' | 'WIP' | NULL | NULL |
| 3 | 'Made Date' | NULL | NULL | 2017-03-07 |
My query is getting pretty complicated, so I'm wondering if I'm taking the wrong approach. Here is what I've done so far.
DECLARE #textcolsUnpivot AS NVARCHAR(MAX),
#datecolsUnpivot AS NVARCHAR(MAX),
#numbercolsUnpivot AS NVARCHAR(MAX),
#query AS NVARCHAR(MAX)
select #textcolsUnpivot
= stuff((select ','+quotename(columnname)
from customproperty
where custompropertytype = 0
order by columnname
for xml path('')), 1, 1, '')
select #datecolsUnpivot
= stuff((select ','+quotename(columnname)
from customproperty
where custompropertytype = 1
order by columnname
for xml path('')), 1, 1, '')
select #numbercolsUnpivot
= stuff((select ','+quotename(columnname)
from customproperty
where custompropertytype = 2
order by columnname
for xml path('')), 1, 1, '')
set #query
= 'select id, CPName, CPTextValue, NULL as CPDateValue, NULL as CPNumberValue from
(select id, CPTextValue, CPCol from item
unpivot
(
CPTextValue
for CPCol in ('+ #textcolsunpivot +')
) unpiv ) as pv
inner join
(select columnname, name as CPName, custompropertytype from customproperty) as cp
on cp.columnname = pv.CPCol
union
select id, CPName, NULL, CPDateValue, NULL from
(select id, CPDateValue, CPCol from item
unpivot
(
CPDateValue
for CPCol in ('+ #datecolsunpivot +')
) unpiv ) as pv
inner join
(select columnname, name as CPName, custompropertytype from customproperty) as cp
on cp.columnname = pv.CPCol
union
select id, CPName, NULL, NULL, CPNumberValue from
(select id, CPNumberValue, CPCol from item
unpivot
(
CPNumberValue
for CPCol in ('+ #numbercolsunpivot +')
) unpiv ) as pv
inner join
(select columnname, name as CPName, custompropertytype from customproperty) as cp
on cp.columnname = pv.CPCol
'
exec sp_executesql #query;
For additional clarification, the schema of the tables are:
Item:
Id - pk, (it's actually a GUID, but I'm using an int for this example.), not null
CustomString00 through CustomString199 - nvarchar(max), null
CustomDate00 through CustomDate199 - datetime, null
CustomNumber00 through CustomNumber199 - float, null
CustomProperty:
Name - nvarchar(100),not null
Type - int, not null
ColumnName - nvarchar(50), not null
If I was to continue my current approach, I think I need to now PIVOT the results of my previous query to put it in the form that I'm looking for. Is this correct?