SQL Server Temporary Table With Master and Transaction Tables

Description

This article explains temporary tables with example in SQL Server.

When we develop an application, in many cases we need to use temporary tables in our applications.

So let's have a look at a practical example of how to create a Stored Procedure to insert values into multiple tables in SQL Server using a temporary table.

The example is developed in SQL Server 2012 using the SQL Server Management Studio.

The requirement was to use a master table containing an id as the primary key. The other table was a Transaction table with a foreign key.

The master table id should be transferred to the transaction table.

First we have created two tables named MasterTable and TransactionTable.

Create table MasterTable (
Id int identity (1, 1),
Name varchar(50)
)

Create table TransactionTable (
t_id int identity (1, 1),
fk_Id int,
(Foreign key)
)

Then we created a temporary table on the master table.

Create table #tempTest
(
Cid int identity (1, 1),
Id int,
Name varchar(50)
)

Insert into #tempTest(Id,Name)
select
Id,
Name
from  MasterTable

Now you can see the original data in a temporary table using a select statement.

select * from #tempTest

When to use a temporary table

If there is logic inside a Stored Procedure that involves manipulation of data that cannot be done within a single query, then in such cases, the output of one query / intermediate result can be stored in a temporary table that then participates in further manipulation via joins and so on to achieve the final result.

Now we need to transfer the primary key id in the transaction table. To do that we created a loop on the master table to visit all the ids one by one.

Declare @var int = 1 While @var <= ( Select COUNT(*) from #tempTest)
    Begin Declare @tempid int
  Select
    @tempid = Id
  from
    #tempTest where Cid=@var
  select
    @tempid Insert into MasterTable(Name)
  Select name from  MasterTable
  where Id = @tempid --select * from #tempTest
  set
    @var = @var + 1
  Drop table #tempTest
    END

Now we need to fetch the master table id and insert into the transaction table. In the master table we have applied an identity with a primary key. So we can fetch the last inserted value from the master table using @@IDENTITY.

Declare @identity int
set @identity =@@IDENTITY
--select @identity
Insert into TransactionTable(fk_Id)
Select @identity from Acct_Test2 where fk_id=@tempid

The following is the Stored Procedure to do that.

Create Procedure Procedurename
As
Create table #tempTest
(
Cid int identity (1,1),
Id int,
Name varchar(50)
)
Insert into #tempTest(Id,Name)
select Id, Name from MasterTable

--select COUNT(*) from #tempTest
select * from #tempTest

Declare @var int=1
While @var <= (Select COUNT(*) from #tempTest)
Begin
Declare @tempid int
Select @tempid = Id from #tempTest where Cid=@var
select @tempid

Insert into MasterTable(Name)
Select name from MasterTable where Id=@tempid
--select * from #tempTest

Declare @identity int
set @identity =@@IDENTITY
--select @identity -76

Insert into TransactionTable(fk_Id)
Select @identity from TransactionTable where fk_id=@tempid

set @var=@var+1
Drop table #tempTest
END
--SELECT * FROM [RTU_Test].[dbo].[MasterTable]
--Select fk_id from TransactionTable