Question

i’d appreciate some help putting together a sql script to copy data from one table to another. essentially what i need to do for each row in the source table is aggregate the column values and store them into a single column in the target table.

TableA: ID, ColumnA, ColumnB, ColumnC TableB: Identity, ColumnX 

so, ColumnX needs to be something like ‘ColumnA, ColumnB, ColumnC’.

in addition though, i need to keep track of each TableA.ID -> SCOPE_IDENTITY() mapping in order to update a third table.

thanks in advance!

EDIT: TableA.ID is not the same as TableB.Identity. TableB.Identity will return a new identity value on insert. so either i need to store the mapping in a temp table or update TableC with each insert into TableB.

Answer 1

Here is a row-by-row processing example. This will provide you the results in a way where you can process each row at a time. Or you can use TableC at the end and do whatever processing you need to do.

However, it would be a lot faster if you added an extra column to TableB (Called TableA_ID) and just INSERTED the result into it. You would have instant access to TableA.ID and TableB.Identity. But without knowing your exact situation, this may not be feasible. (But you could always add the column and then drop it afterwards!)

USE tempdb GO  CREATE TABLE TableA (     ID int NOT NULL PRIMARY KEY,     ColumnA varchar(10) NOT NULL,     ColumnB varchar(10) NOT NULL,     ColumnC varchar(10) NOT NULL )  CREATE TABLE TableB (     [Identity]  int IDENTITY(1,1) NOT NULL PRIMARY KEY,     ColumnX varchar(30) NOT NULL )  CREATE TABLE TableC (     TableA_ID  int NOT NULL,     TableB_ID  int NOT NULL,     PRIMARY KEY (TableA_ID, TableB_ID) )  GO  INSERT INTO TableA VALUES (1, 'A', 'A', 'A') INSERT INTO TableA VALUES (2, 'A', 'A', 'B') INSERT INTO TableA VALUES (3, 'A', 'A', 'C') INSERT INTO TableA VALUES (11, 'A', 'B', 'A') INSERT INTO TableA VALUES (12, 'A', 'B', 'B') INSERT INTO TableA VALUES (13, 'A', 'B', 'C') INSERT INTO TableA VALUES (21, 'A', 'C', 'A') INSERT INTO TableA VALUES (22, 'A', 'C', 'B') INSERT INTO TableA VALUES (23, 'A', 'C', 'C') GO  -- Do row-by-row processing to get the desired results SET NOCOUNT ON DECLARE @TableA_ID int DECLARE @TableB_Identity int DECLARE @ColumnX varchar(100)  SET @TableA_ID = 0  WHILE 1=1 BEGIN    -- Get the next row to process   SELECT TOP 1      @TableA_ID=ID,     @ColumnX = ColumnA + ColumnB + ColumnC   FROM TableA   WHERE ID > @TableA_ID    -- Check if we are all done   IF @@ROWCOUNT = 0     BREAK    -- Insert row into TableB   INSERT INTO TableB (ColumnX)     SELECT @ColumnX    -- Get the identity of the new row   SET @TableB_Identity = SCOPE_IDENTITY()    -- At this point, you have @TableA_ID and @TableB_Identity.   -- Go to town with whatever extra processing you need to do   INSERT INTO TableC (TableA_ID, TableB_ID)     SELECT @TableA_ID, @TableB_Identity  END GO  SELECT * FROM TableC GO 

SELECT * FROM TableA

ID          ColumnA    ColumnB    ColumnC ----------- ---------- ---------- ---------- 1           A          A          A 2           A          A          B 3           A          A          C 11          A          B          A 12          A          B          B 13          A          B          C 21          A          C          A 22          A          C          B 23          A          C          C 

SELECT * FROM TableB

Identity    ColumnX ----------- ------------------------------ 1           AAA 2           AAB 3           AAC 4           ABA 5           ABB 6           ABC 7           ACA 8           ACB 9           ACC 

SELECT * FROM TableC

TableA_ID   TableB_ID ----------- ----------- 1           1 2           2 3           3 11          4 12          5 13          6 21          7 22          8 23          9