SQL dynamic columns and Update multiple columns - sql

Question

I have a table UserPermission which has a number of columns of TINYINT type. e.g Read, Write, Update, Delete, Access etc.
I get three parameters in the stored procedure: #UserId, #ColNames, #ColValues where #ColNames and #ColValues are comma separated values.
How can I insert or update the table row (if already exists) with the passed column names and corresponding values.
I try to write the dynamic query which runs fine for INSERT but I was unable to write the UPDATE query dynamically with each column and its value to be concatenate.
Any response would be appreciated
Thanks in advance.

Answer 1

This is a somewhat dirty way to do what you require. However, if you create the following Stored Procedure:
CREATE FUNCTION [dbo].[stringSplit]
(
#String NVARCHAR(4000),
#Delimiter NCHAR(1)
)
RETURNS TABLE
AS
RETURN
(
WITH Split(stpos,endpos)
AS(
SELECT 0 AS stpos, CHARINDEX(#Delimiter,#String) AS endpos
UNION ALL
SELECT endpos+1, CHARINDEX(#Delimiter,#String,endpos+1)
FROM Split
WHERE endpos > 0
)
SELECT 'Id' = ROW_NUMBER() OVER (ORDER BY (SELECT 1)),
'Data' = SUBSTRING(#String,stpos,COALESCE(NULLIF(endpos,0),LEN(#String)+1)-stpos)
FROM Split
)
You can then use that Procedure to join the data together:
DECLARE #TotalCols INT
DECLARE #TotalVals INT
SET #TotalCols = (
SELECT COUNT(ID) AS Total
FROM dbo.stringSplit('department, teamlead', ',')
);
SET #TotalVals = (
SELECT COUNT(ID) AS Total
FROM dbo.stringSplit('IT, Bob', ',')
);
IF #TotalCols = #TotalVals
BEGIN
IF OBJECT_ID('tempdb..#temptable') IS NOT NULL
DROP TABLE #temptable
CREATE TABLE #temptable (
ColName VARCHAR(MAX) NULL
,ColValue VARCHAR(MAX) NULL
)
INSERT INTO #temptable
SELECT a.DATA
,b.DATA
FROM dbo.stringSplit('department, teamlead', ',') AS a
INNER JOIN dbo.stringSplit('IT, Bob', ',') AS b ON a.Id = b.Id
SELECT *
FROM #temptable;
END
It's not very efficient, but it will bring you the desired results.
You can then use the temp table to update, insert and delete as required.

Answer 2

Instead of having a comma delimited list I would create a separate parameter for each Column and make its default value to NULL and in the code update nothing if its null or insert 0. Something like this....
CREATE PROCEDURE usp_UserPermissions
#UserID INT
,#Update INT = NULL --<-- Make default values NULL
,#Delete INT = NULL
,#Read INT = NULL
,#Write INT = NULL
,#Access INT = NULL
AS
BEGIN
SET NOCOUNT ON;
Declare #t TABLE (UserID INT, [Update] INT,[Read] INT
,[Write] INT,[Delete] INT,[Access] INT)
INSERT INTO #t (Userid, [Update],[Read],[Write],[Delete],[Access])
VALUES (#UserID , #Update , #Read, #Write , #Delete, #Access)
IF EXISTS (SELECT 1 FROM UserPermission WHERE UserID = #UserID)
BEGIN
UPDATE up -- Only update if a value was provided else update to itself
SET up.[Read] = ISNULL(t.[Read] , up.[Read])
,up.[Write] = ISNULL(t.[Write] , up.[Write])
,up.[Update] = ISNULL(t.[Update] , up.[Update])
,up.[Delete] = ISNULL(t.[Delete] , up.[Delete])
,up.[Access] = ISNULL(t.[Access] , up.[Access])
FROM UserPermission up
INNER JOIN #t t ON up.UserID = t.UserID
END
ELSE
BEGIN
-- if already no row exists for that User add a row
-- If no value was passed for a column add 0 as default
INSERT INTO UserPermission (Userid, [Update],[Read],[Write],[Delete],[Access])
SELECT Userid
, ISNULL([Update], 0)
, ISNULL([Read], 0)
, ISNULL([Write], 0)
, ISNULL([Delete], 0)
, ISNULL([Access], 0)
FROM #t
END
END