Partition in Existing Table in SQL Server.

Step1 : Create Multiple File Group Database.

CREATE DATABASE MULTIFILEGROUP
ON PRIMARY
(NAME = N'MFGTest_1', FILENAME = N'C:\SQL Server\MulipleFilegroup\MFGTest_1.mdf', SIZE = 5124KB, FILEGROWTH = 10% ),
FILEGROUP [SECONDARY]
(NAME = N'MFGTest_2', FILENAME = N'C:\SQL Server\MulipleFilegroup\MFGTest_2.ndf', SIZE = 1024KB, FILEGROWTH = 10% )
LOG ON
( NAME = N'MFGTest_Log', FILENAME = N'C:\SQL Server\MulipleFilegroup\MFGTest_Log.ldf', SIZE = 1024KB, FILEGROWTH = 10% )

Step2 : Create Simple Table with out partition.

USE [MULTIFILEGROUP]
GO
--Create Simple Table.
CREATE TABLE [DBO].[Tblpartition_existingtable]
(
[Seq]           [INT] IDENTITY(1, 1) NOT NULL,
[Partitionname] [VARCHAR](20),
[Split_value]   [INT] NOT NULL,
CONSTRAINT [PK_TBLPARTITION_EXISTINGTABLE] PRIMARY KEY CLUSTERED ( [Seq]
ASC, [Split_value] ASC )
)

Step3 : Insert sample data into table with out partition.

--Insert Data into Table.
DECLARE @cnt INT
SET @cnt =0
WHILE ( @Cnt < 10000 )
  BEGIN
      IF ( @cnt < 5000 )
        INSERT INTO Tblpartition_existingtable
        VALUES     ('Primary', @cnt)
      ELSE
        INSERT INTO Tblpartition_existingtable
        VALUES     ('Secondary', @cnt)
      SET @cnt = @cnt + 2
  END

Currently we have created simple table without partition and now the step starts to create partition in existing table.

Step4 : Create partition function.

--Create Partition Function
CREATE PARTITION FUNCTION FN_PARTITION_TBLPARTITION_EXISTINGTABLE (INT) AS RANGE RIGHT FOR
VALUES(5000)

Step5 : Create partition scheme.

--Create Parition Scheme
CREATE PARTITION SCHEME SCH_PARTITION_TBLPARTITION_EXISTINGTABLE AS PARTITION
FN_PARTITION_TBLPARTITION_EXISTINGTABLE TO([PRIMARY], [SECONDARY])

Step6 : Drop primary key if you clustered index based on primary key.

--Drop Primary Key (Here i have created primary key so i have to drop primary key)
ALTER TABLE Tblpartition_existingtable
DROP CONSTRAINT PK_TBLPARTITION_EXISTINGTABLE

Step7 : Drop clustered index if your index is independent of primary key.

--Drop and Recreate Clustered Index (It is optional, you can use if you have created clustered index without primary key)
DROP INDEX PK_TBLPARTITION_EXISTINGTABLE ON TBLPARTITION_EXISTINGTABLE

Step8 : Alter table and apply partition scheme.

--Alter Table to apply Partition Schema
ALTER TABLE Tblpartition_existingtable
ADD PRIMARY KEY (Seq, Split_value) ON SCH_PARTITION_TBLPARTITION_EXISTINGTABLE
(SPLIT_VALUE)

Step9 : Check row count by partion using below query.

SELECT T.Name             AS Table_name,
Ps.Name            AS Partition_scheme,
Pf.Name            AS Partition_function,
CASE
WHEN Pf.Boundary_value_on_right = 1 THEN 'RIGHT'
ELSE 'LEFT'
END                AS Range_type,
P.Partition_number AS Partition_number,
P.Rows             AS Numberofrows
FROM   SYS.Tables T
JOIN SYS.Indexes I
ON T.Object_id = I.Object_id
JOIN SYS.Partition_schemes Ps
ON I.Data_space_id = Ps.Data_space_id
JOIN SYS.Partition_functions Pf
ON Ps.Function_id = Pf.Function_id
JOIN SYS.Partitions P
ON I.Object_id = P.Object_id
AND I.Index_id = P.Index_id
WHERE  I.Index_id < 2 --Filter for Clustered Index
ORDER  BY P.Partition_number

Regards,
Nirav Gajjar