How to insert data from source table (but different columns) into two different tables in SQL Server - sql

Question

I have a staging table titled [Staging]. The data from this table needs to be inserted into two separate tables. Half of the columns go to the first table (we'll call it [Table1]) and the other half go to a second table (we'll call it [Table2])
Both of these tables have a column titled "ChainID". In [Table1] the ChainID is an identity column. In [Table2] it's not.
The ChainID is the one column that links these two tables together for when we need to query this data.
I currently have it set up to where it will do the insert into [Table1] which then generates the new ChainIds. I can use "OUTPUT INSERTED.ChainID" to get the ChainId's that were generated but my problem is tying this back to the original staging table in order to grab the rest of the data for the second table.
DECLARE #Staging TABLE
(
[RowID] [int],
[ChainID] [varchar](50) ,
[LoanNo] [varchar](50) ,
[AssignmentFrom] [varchar](4000),
[AssignmentTo] [varchar](4000),
[CustodianUID] [nvarchar](100) null,
[DocCode] [nvarchar](100) null
)
INSERT
#Staging
SELECT
RowID,
ChainID,
LoanNo,
AssignmentFrom,
AssignmentTo,
CustodianUID,
DocCode
FROM
[MDR_CSV].[dbo].[TblCollateralAssignmentChainImport]
WHERE
UploadID = 1
This is where we do the insert into the first table which generates the new chainIds that will be needed to merge into Table2.
INSERT INTO
Table1
SELECT
LoanNo,
AssignmentFrom,
AssignmentTo,
CustodianUID
FROM
#Assignments AS MDRCA
WHERE
MDRCA.ChainID IS NULL
Now I need to insert the data from the DocCode field into Table2. I can get the list of newly generated ChainIds by doing something such as
OUTPUT INSERTED.ChainID
But that doesn't help being able to tie the newly generated chainId's back to the corresponding data rows from the Staging table in order to do the insert into Table2.

Answer 1

I ended up figuring out a solution. I used a curser to go through each row of data from the staging table one by one. That allowed me to do the insert into the first table (with only the pertinent columns from the staging table) along with doing an OUTPUT.INSTERTED ChainID and stored that newly generated ChainID into a table variable. I then assign that ChainID value to a regular variable by doing
#ChainID = (SELECT TOP 1 * FROM #tableVariable)
I could then use this ChainID to insert into the second table along with the rest of the data from the staging table that pertained to the same row of data (which was possible due to the curser)
Then before the curser loops I drop the table variable and recreate it back at the top of the loop so that the SELECT TOP 1 works correctly each time.
Not sure if it's the best or more efficient way to go about this but at least it worked!
Here's an example showing how I got it to work:
TblCollateralAssignmentChainImport is the Staging Table
temp_tblCollateralAssignment is Table1
temp_CustodianData is Table2
DECLARE #RowID int, #ChainID int;
DECLARE import_cur CURSOR FOR
SELECT RowID
FROM [MDR_CSV].[dbo].[TblCollateralAssignmentChainImport]
WHERE ChainId IS NULL
order by RowID;
OPEN import_cur
FETCH NEXT FROM import_cur
INTO #RowID
WHILE ##FETCH_STATUS = 0
BEGIN
DECLARE #NewlyCreatedChainId table (nChainId int);
INSERT INTO temp_tblCollateralAssignment
OUTPUT INSERTED.ChainID INTO #NewlyCreatedChainId
SELECT LoanNo, AssignmentFrom, AssignmentTo
FROM TblCollateralAssignmentChainImport
WHERE RowId = #RowID
SET #ChainID = (SELECT TOP 1 nChainId FROM #NewlyCreatedChainId)
INSERT INTO temp_CustodianData (ChainID, LoanNo, CustodianUID, DocCode)
SELECT #ChainID, import.LoanNo, import.CustodianUID, import.DocCode
FROM TblCollateralAssignmentChainImport AS import
WHERE RowId = #RowID
DELETE FROM #NewlyCreatedChainId
FETCH NEXT FROM import_cur
INTO #RowID
END
CLOSE import_cur;
DEALLOCATE import_cur;