How to join 2 tables with unequal rows without resulting in a cartesian join

Question

Hello,
This is the first time I have ever posted in any forum so please tell me if I should be doing this better.
Basically I have 2 tables with an unequal number of rows. For demonstration purposes, assume these are my 2 tables:
Table 1:
BaseKey
Letters
A
A
A
B
A
C
B
A
B
B
Table 2:
BaseKey
Numbers
A
1
A
2
B
1
B
2
B
3
I need to join them so that the data would appear like this
BaseKey
Letters
Numbers
A
A
1
A
B
2
A
C
null
B
A
1
B
B
2
B
null
3
Does anyone have any ideas how to do this using T-SQL without creating a cartesian join of 12 rows?
Thanks.

Answer 1

>> This is the first time I have ever posted in any forum so please tell me if I should be doing this better. <<
Please post DDL, so that people do not have to guess what the keys, constraints, Declarative Referential Integrity, data types, etc. in your schema are. Learn to follow ISO-11179 data element naming conventions and formatting rules. Temporal data should
use ISO-8601 formats. Code should be in Standard SQL as much as possible and not local dialect.
This is minimal polite behavior on SQL forums. What you did post is useless! Can you program from it? Neither can we. And we have to do all the extra typing for you.
CREATE TABLE Foo
(base_something  CHAR(1) NOT NULL,
 something_letter CHAR(1) NOT NULL,
 PRIMARY KEY (base_something, something_letter));
INSERT INTO Foo
VALUES ('A', 'A'),
('A', 'B'),
('A', 'C'),
('B', 'A'),
('B', 'B');
CREATE TABLE Bar
(CHAR(1) NOT NULL,
 something_digit CHAR(1) NOT NULL,
 PRIMARY KEY (base_something, something_digit));
INSERT INTO Foo
VALUES ('A', '1'),
('A', '2'),
('B', '1'),
('B', '2'),
('B', '3');
>> I need to join them so that the data would appear like this
base_something Letters Numbers <<
This looks like you are taking two decks of punch cards and merging them together, without any logical rules, just physical position in their decks relative to the base_something groups.
WITH Foo_Deck
AS
(SELECT base_something, something_letter,
       ROW_NUMBER()
        OVER (PARTITION BY base_something
               ORDER BY something_letter) AS card),
Bar_Deck
AS
(SELECT base_something, something_digit,
       ROW_NUMBER()
        OVER (PARTITION BY base_something
               ORDER BY something_digit) AS card),
SELECT F.base_something, F.something_digit, B.something_letter
  FROM Foo_Deck AS F
       LEFT OUTER JOIN
       Bar_Deck AS B
       ON B.base_something = F.base_something
          AND B.card = F.card;
--CELKO-- Books in Celko Series for Morgan-Kaufmann Publishing: Analytics and OLAP in SQL / Data and Databases: Concepts in Practice Data / Measurements and Standards in SQL SQL for Smarties / SQL Programming Style / SQL Puzzles and Answers / Thinking
in Sets / Trees and Hierarchies in SQL