sql server 2012

hi,
   why we are using .. in tempdb

  if object_id ('tempdb..#tempcheck') is not null
 drop table #tempcheck

i know its stored in tempdatabase  we access from tempdb to our db we using .. why its only .. any specific reason to put ..
meaning of ..
kowsika deviAsked:
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NerdsOfTechTechnology ScientistCommented:
We will need additional information about the problem, example input, a full SQL statement, and expected output.

To summarize, temp tables are namely used for doing arbitrary calculations or running user-written programs without referencing a data source, to guarantee a known result.

Many database systems have a built in temporary table named DUAL. However, in SQL Server, a temporary table would be an actual table that is created and destroyed for a similar purpose, or simply a SELECT without a FROM clause.

Moreover, in SQL Server, you can also use common table expression (CTE). A CTE resembles a subquery, but unlike subqueries, you can re-use the same data set over and over again in your code (much like a temp table).

SELECT 2*2 AS twosquared 

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kowsika deviAuthor Commented:
sorry sir....

i need to know why we are using ..
linked server also we are connecting one server to another server db using  ..
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Ryan ChongCommented:
if object_id ('tempdb..#tempcheck') is not null
 drop table #tempcheck
I would think at the later stage of the same codes, it's creating a temp table named: #tempcheck
it would probably creating an error if you creating that temp table again.
There is already an object named '#tempcheck' in the database.

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hence, it would be good to drop it if it's exists before you run the codes that generating this temp table.
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kowsika deviAuthor Commented:
iam asking about .. sir not tempdb and if object_id

i need why we using  2 dots only why cant we use 1 dot or 3 dot is that any specific reason for that 2 dots . this is my question
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Ryan ChongCommented:
i need why we using  2 dots only why cant we use 1 dot or 3 dot is that any specific reason for that 2 dots .
that would simply because it's the syntax to be used...
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NerdsOfTechTechnology ScientistCommented:
In SQL, dots or period characters (.) could be used to separate objects such as schema(database), tables, and fields.

So ('tempdb..#tempcheck') would mean 'tempdb' (database) . NULL (table) .#tempcheck (field)
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Ryan ChongCommented:
i think it probably means:

DROP TABLE [ database_name . [ schema_name ] . | schema_name . ] table_name   
[;] 

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Nitin SontakkeDeveloperCommented:
Typically, fully qualified names of the objects in SQL Server are [servername].[databasename].[schemaname].[objectname]. Hope it is clear to you up-to this point.

Furthermore, typically, whatever is default, it is omitted altogether. For example, if you want to access object on same server and same database, you never mention it. You only mention [schemaname].[objectname]. In fact, in stored procedures and elsewhere, you will also notice that default [schemaname], which [dbo] is also omitted altogether.

Now, you want to check the existence of the object not in your database but in other database on the same server and different database and default schema....so you write [tempdb]..[tablename]. Hope that sort of clarifies.
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NerdsOfTechTechnology ScientistCommented:
The complete name of an object is made up of four identifiers: the server name, database name, schema name, and object name. They appear in the following format:

server_name.[database_name].[schema_name].object_name

| database_name.[schema_name].object_name

| schema_name.object_name

| object_name

The server, database, and owner names are known as the qualifiers of the object name. When you refer to an object, you do not have to specify the server, database, and owner. The qualifiers can be omitted by marking their positions with a period. The valid forms of object names include the following:

server_name.database_name.schema_name.object_name

server_name.database_name..object_name

server_name..schema_name.object_name

server_name...object_name

database_name.schema_name.object_name

database_name..object_name

schema_name.object_name

object_name


https://technet.microsoft.com/en-us/library/ms187879(v=sql.105).aspx
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kowsika deviAuthor Commented:
thanku  Nitin Sontakke ,Ryan Chong,NerdsOfTech for ur help . now am understand for separate objects using .
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kowsika deviAuthor Commented:
thanku nitin
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NerdsOfTechTechnology ScientistCommented:
No problem, in my last post you will see why 2 dots are used in a row, opposed to 1 or 3 (which are valid depending on the circumstances)
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