Question

We have an auditing system which logs all the changes that occur in all the system tables. Basically, this is how the AuditLog table looks like:

Currently I am creating a couple of sql views to query different kind information. Everything is ok except for one point. If you take a look at the image again, you will see I have a SubscriptionMetadata table which is a key-value pairs table with 2 fields (MetaName and MetaValue). What the immage shows is that the subscription has a new watermark which value is ‘Licensed copy: Fullname, Company, V…’.

What I need is transform, in my view, these two rows in just one with the following form:

41 - Insert - SubscriptionMetadata - 2012-10-19 - 53DA4XXXXXX - Watermark -  Licensed copy: Fullname, Company, V...

I really cannot imagine how I can do it or search for it neither.

There is another problem (I think), these rows comes always in that order: MetaName first and then MetaValue. That´s the only way to know they are related.

Could you help me, please?

Answer 1

While I cannot see your full table structure you can transform the data the following way. Both of these solutions will place the data in separate columns:

;with data(id, [action], [type], [date], [col], metatype, value) as
(
    select 41, 'Insert', 'SubscriptionMetaData', '2012-10-19', '53DA4XXX','Metaname', 'Watermark'
    union all
    select 41, 'Insert', 'SubscriptionMetaData', '2012-10-19', '53DA4XXX','MetaValue', 'Licensed copy: Fullname, Company'
) 
select id, action, type, date, col,
    MAX(case when metatype = 'Metaname' then value end) Name,
    MAX(case when metatype = 'MetaValue' then value end) Value
from data
group by id, action, type, date, col

See SQL Fiddle with Demo

Or you can use a PIVOT on the data to get the same result:

;with data(id, [action], [type], [date], [col], metatype, value) as
(
    select 41, 'Insert', 'SubscriptionMetaData', '2012-10-19', '53DA4XXX','Metaname', 'Watermark'
    union all
    select 41, 'Insert', 'SubscriptionMetaData', '2012-10-19', '53DA4XXX','MetaValue', 'Licensed copy: Fullname, Company'
) 
select *
from
(
    select id, [action], [type], [date], [col], metatype, value
    from data
) src
pivot
(
    max(value)
    for metatype in (Metaname, MetaValue)
) piv

See SQL Fiddle with Demo

Both produce the same result:

| ID | ACTION |                 TYPE |       DATE |      COL |      NAME |                            VALUE |
-------------------------------------------------------------------------------------------------------------
| 41 | Insert | SubscriptionMetaData | 2012-10-19 | 53DA4XXX | Watermark | Licensed copy: Fullname, Company |