Why is my sql code throwing errors - sql-server

Question

Here's the concept: when a user selects a user list from the frontend treeview and clicks the Save button, the table which contains the mapping for role to users must clear itself of all the users with the role and re insert records with the given role id and userlist.
I am using following stored procedure and function:
Stored procedure:
ALTER PROCEDURE [dbo].[AssignRoleToUser]
#RoleID INT = 0,
#UserID varchar(max) = ''
AS
BEGIN
delete from UserRole
where RoleID = #RoleID
AND UserID IN (SELECT UserID FROM UserRole)
INSERT INTO UserRole(UserID, RoleId)
SELECT id, #RoleID
FROM dbo.CSVToTable(#UserID)
END
Function
CREATE FUNCTION [dbo].[CSVToTable] (#InStr VARCHAR(MAX))
RETURNS #TempTab TABLE (id int not null)
AS
BEGIN
;-- Ensure input ends with comma
SET #InStr = REPLACE(#InStr + ',', ',,', ',')
DECLARE #SP INT
DECLARE #VALUE VARCHAR(1000)
WHILE PATINDEX('%,%', #INSTR ) <> 0
BEGIN
SELECT #SP = PATINDEX('%,%',#INSTR)
SELECT #VALUE = LEFT(#INSTR , #SP - 1)
SELECT #INSTR = STUFF(#INSTR, 1, #SP, '')
INSERT INTO #TempTab(id) VALUES (#VALUE)
END
RETURN
END
But I get this error
Msg 217, Level 16, State 1, Procedure AssignRoleToUser, Line 7
Maximum stored procedure, function, trigger, or view nesting level exceeded (limit 32).

Answer 1

Error is exactly saying what went wrong as below, along with the line number.
Msg 217, Level 16, State 1, Procedure AssignRoleToUser, Line 7
Take out the line 7 from your procedure AssignRoleToUser
INSERT INTO UserRole(UserID, RoleId) SELECT id, #RoleID
FROM dbo.CSVToTable(#UserID)
As can be seen, it's calling another function named dbo.CSVToTable. Likewise dbo.CSVToTable may be calling some other procedure\function and that's how the nesting depth has reached to maximum limit. so the error is.
Also, In Line 6 in your procedure AND UserID IN (Select UserID from UserRole) is not needed. which makes it as below
delete from UserRole where RoleID = #RoleID
You can run the below query which will list out all procedure that gets called in chain when running AssignRoleToUser procedure (Query observed from Get All Nested Stored Procedures)
SELECT * FROM
(SELECT NAME AS ProcedureName, SUBSTRING(( SELECT ', ' + OBJDEP.NAME
FROM sysdepends
INNER JOIN sys.objects OBJ ON sysdepends.ID = OBJ.OBJECT_ID
INNER JOIN sys.objects OBJDEP ON sysdepends.DEPID = OBJDEP.OBJECT_ID
WHERE obj.type = 'P'
AND Objdep.type = 'P'
AND sysdepends.id = procs.object_id
ORDER BY OBJ.name
FOR
XML PATH('')
), 2, 8000) AS NestedProcedures
FROM sys.procedures procs )InnerTab
WHERE NestedProcedures IS NOT NULL
AND NAME = 'AssignRoleToUser'

Answer 2

The error says that you have a call to a procedure, function, or trigger which calls another one which calls another one, etc etc, until the call is 32 calls deep. At this point it's giving and saying 'too much!'.
Do you have any triggers on the UserRole table? Will they call other things? If so, what will they do? And so on...