How can get ROWINDEX and how can use of rowindex insert database in table by unique key(id) .

Get the maximum ID using max fuction from respective table
declare @rowIndex int
Select @rowIndex = max(columnName) from TableName

Use the @rowIndex in your insert query
Insert into tableName (columnName) values (@rowIndex)

by using this way, u can retrive last rowindex of perticular table

if(@CMD = 'INSERT')
BEGIN
INSERT INTO table_name(column_name) 
    VALUES(Add_your_value)

SET @_RGP = SCOPE_IDENTITY()

SELECT @_RGP AS last_rowindex

END

see below

Declare @t_ID int

-- Write your insert query here like..
INSERT INTO TABLE (c1,c2,c3..) VALUES ('c1',c2,'c3'..)
SELECT @t_ID=@@IDENTITY

-- Use that id into your insert query
INSERT INTO TABLE1 (Column1) VALUES (@t_ID)
INSERT INTO TABLE2 (Column2) VALUES (@t_ID)

My understanding is that you have a table with an identity column (auto number) and you want to retrieve the row index for a given identity value ?

and hope this helps

WITH MyTemp AS
(
    SELECT <<YOUR IDENTITY COLUMN>>,<< COLUMN 2>>,<<COLUMN  3>>
    ROW_NUMBER() OVER (ORDER BY <<YOUR IDENTITY COLUMN>>) AS 'RowNumber'
    FROM Orders
)
SELECT *
FROM MyTemp
where <<YOUR IDENTITY COLUMN>>=10251

folowowing is the query you can run on the SQL Server northwind database and see how it works

WITH OrderedOrders AS
(
    SELECT OrderID,OrderDate,
    ROW_NUMBER() OVER (ORDER BY orderid) AS 'RowNumber'
    FROM Orders
)
SELECT *
FROM OrderedOrders
--where OrderID=10251