Sql script syntax and grammar issues - sql-server

Question

Can someone help please I dont know what I am doing wrong:
IF EXISTS ( SELECT name
FROM sys.tables
WHERE name = N'MemberIdsToDelete' )
DROP TABLE [MemberIdsToDelete];
GO
SELECT mm.memberid ,
mm.aspnetuserid ,
mm.email ,
mm.RowNum AS RowNum
INTO #MemberIdsToDelete
FROM membership.members AS mm
LEFT JOIN aspnet_membership AS asp ON mm.aspnetuserid = asp.userid
LEFT JOIN trade.tradesmen AS tr ON tr.memberid = mm.memberid
WHERE asp.isapproved = 0
AND tr.ImportDPN IS NOT NULL
AND tr.importDPN <> ''
ORDER BY mm.memberid
DECLARE #MaxRownum INT
SET #MaxRownum = ( SELECT MAX(RowNum)
FROM #MemberIdsToDelete
)
DECLARE #Iter INT
SET #Iter = ( SELECT MIN(RowNum)
FROM #MemberIdsToDelete
)
DECLARE #MemberId INT
DECLARE #TrademId INT
DECLARE #UId UNIQUEIDENTIFIER
DECLARE #Successful INT
DECLARE #OutputMessage VARCHAR(200)
DECLARE #Email VARCHAR(100)
DECLARE #Username VARCHAR(100)
SELECT #MemberId = memberId ,
#UId = AspNetUserId
FROM MemberIdsToDelete
SELECT #TrademId = TradesManId
FROM trade.TradesMen
WHERE memberId = #MemberId;
WHILE #Iter <= #MaxRownum
BEGIN
SELECT *
FROM #MemberIdsToDelete
WHERE RowNum = #Iter
--more code here
SET #Iter = #Iter + 1
END
I just want to check if my table MemberIdsToDelete exists, if so drop it,
create MemberIdsToDelete with the results set from the select
loop through MemberIdsToDelete table and perform operations
I am getting error that RowNum does not exist

Answer 1

For a start, to check if a table exists and then drop accordingly, you need to use something like
IF EXISTS (SELECT name
FROM sys.tables
WHERE name = N'MemberIdsToDelete')
DROP TABLE [MemberIdsToDelete];
GO
as for the error, your RowNum column does not exist when you are attempting to reference it. Include it in the SELECT statement
select mm.memberid, mm.aspnetuserid, mm.email, mm.RowNum AS RowNum
into #MemberIdsToDelete
from membership.members as mm
left join aspnet_membership as asp
on mm.aspnetuserid=asp.userid
left join trade.tradesmen as tr
on tr.memberid=mm.memberid
where asp.isapproved = 0 and tr.ImportDPN IS NOT NULL
and tr.importDPN <> ''
order by mm.memberid;
GO
I hope this helps.
Edit. Based on you additional error from your comment. You are now attempting to access a temporary table that does not exist. You must first populate the temporary table #MemberIdsToDelete before attempting to read from it. The invalid column error is down to the same problem. You are attempting to read a column called RowNum from the temporary table which does not exist.
Edit2. Remove the '#' from the #MemberIdsToDelete. You are inserting into a table not a temporary table. Or, Add a # to the select into above (see the code above). This will make it a temporary table as required.

Answer 2

You don't have a RowNum column in that table.
Try:
select mm.memberid, mm.aspnetuserid, mm.email, row_number() over (order by (select 1)) as RowNum
....
This should solve your problem, but I wouldnt actually recommend this idea of looping through the ones to delete.