SQL Server sequence - sql

Question

I want to create a sequence group by a particular column.
I have a table LoanMaster and there is a column called BranchCode. It has branches 1 - 48. I want to generate a sequence number per branch. Like for branch code 1, if it has 10 records then generate a sequence number from 1 - 10, then for branch code 2 if it has 15 records generate number from 1 - 15 and so on.
How is it possible?

Answer 1

Use ROW_NUMBER:
SELECT
BranchCode,
[rn] = ROW_NUMBER() OVER(PARTITION BY BranchCode ORDER BY BranchCode)
FROM LoanMaster
ORDER BY BranchCode, rn
#EDIT:#
To start from arbitrary value just add it:
SqlFiddleDemo
SELECT
BranchCode,
[rn] = ROW_NUMBER() OVER(PARTITION BY BranchCode ORDER BY BranchCode) + 100
FROM LoanMaster
ORDER BY BranchCode, rn
#EDIT 2:#
Demo2
CREATE TABLE #LoanMaster(Id INT, LeadsID1 INT, LBrCode INT);
INSERT INTO #LoanMaster(Id, LBrCode)
VALUES (1,1), (2,1), (3,1), (4,1), (5,2), (6,2), (7,2);
;WITH cte AS
(
SELECT
Id,
LBrCode,
[RowNumber] = ROW_NUMBER() OVER(PARTITION BY LBrCode ORDER BY LBrCode) + 2405
FROM #LoanMaster
)
UPDATE T1
SET LeadsID1=c.RowNumber
FROM #LoanMaster AS T1
JOIN cte c
ON c.LBrCode=T1.LBrCode
AND c.Id = T1.Id
WHERE c.LBrCode=1;
SELECT *
FROM #LoanMaster;
This is my last update (accept answer or not) because initial question was answered long ago, for future:
you should ask specific question
provide actual table structures + SQLFiddle
provide desired output
specify what you want to achieve query/update
specify edge cases
Writing in comments more and more demands is not how SO works.