What does 'reference..' mean in SQL syntax?

Question

from
[PMDB].[dbo].PROJECT P
inner join PROJWBS PW on P.proj_id = PW.proj_id
and PW.proj_node_flag = 'Y' and PW.wbs_short_name not like '%- B%'
and PW.status_code <> 'WS_Planned' and PW.status_code <> 'WS_Whatif'
inner join [PMDB].[dbo].TASKSUM TS on PW.proj_id = TS.proj_id and PW.wbs_id = TS.wbs_id
inner join reference..fiscal_year_qtr_month FYQM on isnull(TS.act_end_date,P.scd_end_date) > FYQM.fiscal_month_begin_datetime
and isnull(TS.act_end_date,P.scd_end_date) <= FYQM.fiscal_month_end_datetime
inner join reference..mfg_year_month_ww MYMW on isnull(TS.act_end_date,P.scd_end_date) > MYMW.mfg_ww_begin_datetime
a

I have tried the internet, but just don't understand what does the 'reference..' mean here. Am I missing something?

Answer 1

reference is a database name. In between the database name and the object name goes the schema.

So if you want to query from sys.database_files in master , you would say:

SELECT name FROM master.sys.database_files;
---- database ---^^^^^^
------------- schema ---^^^
----------------- object ---^^^^^^^^^^^^^^

You can leave out the schema if you know the entity name is unambiguous. For catalog views/DMVs, you can't leave it out, but if you're using your default schema (usually dbo), you can leave out the explicit reference. Not that that's a good idea .

Answer 2

reference..mfg_year_month_ww

is the short hand for

reference.dbo.mfg_year_month_ww

basically it means use default schema.

Answer 3

That's T-SQL (Microsoft-specific) syntax indicating the table's name and owner. The default owner is "dbo". The default database is whichever one you're currenting "using".

Here are more details:

http://examplesql.com/sqlserver-t-sql-tsql/dbo-dotdot-syntax/

SELECT * FROM AdventureWorks2008.dbo.AWBuildVersion;

Truth be told, it isn't rocket science. '..' can be used as a replacement for dbo when referring to the default schema in a tsql query. If you need to access the default database frequenty, the dbo .. syntax shortcut can greatly increase your efficiency.