How to combine columns from 2 tables into 1 without using JOIN - sql

Question

I am using SQL Server 2008. I have 2 table variables like
FirstName
==========
Little
John
Baby
LastName
==========
Timmy
Doe
Jessica
And I want the result table be:
First Last
=====================
Little Timmy
John Doe
Baby Jessica
Note that there is no PK can join the 2 tables. I am trying to use a cursor but not sure how to start.
---- Updated -----
I know it's a rare case, but I am writing a script to clean up legacy data. The only way we know "Little" goes with "Timmy" is that they are both the first record of the table. Would it help if we had PK for the tables but there is no relation?
ID FirstName
==========
1 Little
2 John
3 Baby
----------
ID LastName
==========
4 Timmy
5 Doe
6 Jessica
----------
I am not familiar with TSQL so I thought I can loop through the 2 tables like looping through Arrays in memory.

Answer 1

You could try something like this, to match up based on row numbers:
SELECT FirstName AS First, LastName AS Last
FROM
(
SELECT ROW_NUMBER() OVER (ORDER BY ID) AS RowNum, FirstName
FROM FirstName
) t1
INNER JOIN
(
SELECT ROW_NUMBER() OVER (ORDER BY ID) AS RowNum, LastName
FROM LastName
) t2
ON t1.RowNum = t2.RowNum
But don't take this as a signal that you don't need keys.

Answer 2

You can't reliably join these two table variables without identities. Assuming they are being populated in an ordinal manner in the first place, each table could be created with identities as follows:
DECLARE #first TABLE(ID INT IDENTITY(1,1), NameFirst VARCHAR(30));
DECLARE #last TABLE(ID INT IDENTITY(1,1), NameLast VARCHAR(30));
-- Note that we don't need to list column names here
INSERT INTO #first VALUES('Little');
INSERT INTO #first VALUES('John');
INSERT INTO #first VALUES('Baby');
INSERT INTO #last VALUES('Timmy');
INSERT INTO #last VALUES('Doe');
INSERT INTO #last VALUES('Jessica');
SELECT n1.NameFirst
, n2.NameLast
FROM #first n1
INNER JOIN #last n2 ON n1.ID=n2.ID;
Result:
NameFirst NameLast
------------------------------ ------------------------------
Little Timmy
John Doe
Baby Jessica

Answer 3

There is no such thing as a "first record". Reading order is totally undefined. This holds true in practice as well! You will see random row order in practice.
You need to define a sorting order. After doing that you can query like this:
SELECT FirstName AS First, LastName AS Last
FROM
(
SELECT ROW_NUMBER() OVER (ORDER BY ID) AS r, FirstName
FROM FirstName
) t1
INNER JOIN
(
SELECT ROW_NUMBER() OVER (ORDER BY ID) AS r, LastName
FROM LastName
) t2
ON t1.r = t2.r
Notice the placeholder "SORT ORDER HERE". Need to fill that in. Example: "ID" or "FirstName".
Edit: Having seen your edit I added sort order on ID. This will work now.

Answer 4

Here is a hack, that might work in your case:
select t1.id, t1.name, t2.name
from (select name, row_number() over (partition by null order by (select NULL)) as id
from t1
) t1 join
(select name, row_number() over (partition by null order by (select NULL)) as id
from t2
) t2
on t1.id = t2.id
In my experience, the row_number() with the subquery for the order by means that no sort is actually done, but the rows are brought in sequentially. This is more likely to work if you are using a single threaded instance.
And, I don't guarantee that it will work! Definitely check the results! If this doesn't work, you might be able to get the same effect by using temporary tables.
Is this data coming from outside the database world? If you have to perform this process more than once, then you should handle the problem either externally or on input into the database.

Answer 5

Building on solution #JohnDewey presented, you can sort the records into the table variables. In practice, it will create a relation between the values based on the order of the records:
DECLARE #first TABLE(sequence INT IDENTITY(1,1), FirstName VARCHAR(30));
DECLARE #last TABLE(sequence INT IDENTITY(1,1), LastName VARCHAR(30));
INSERT INTO #first(FirstName)
SELECT FirstName FROM TableFisrt ORDER BY id;
-- sequence FirstName
-- ======== =========
-- 1 Little
-- 2 John
-- 3 Baby
INSERT INTO #last(LastName)
SELECT FirstName FROM TableLast ORDER BY id;
-- sequence LastName
-- ======== =========
-- 1 Timmy
-- 2 Doe
-- 3 Jessica
SELECT frs.FirstName, lst.LastName
FROM #first frs
INNER JOIN #last lst ON frs.sequence = lst.sequence;
-- sequence FirstName
-- ======== =========
-- Little Timmy
-- John Doe
-- Baby Jessica