How to understand the SQL SYNTAN which join a table to itself without using INNER JOIN?

Question

There is a TABLE name is team, total 1 column 'name' with 4 records ('a', 'b', 'c', 'd') representing four football teams.

Requires: Using one SQL syntax to show all the possible combinations of tow team.

I just learned about self_join so i used this:

SELECT a.name, b.name
FROM team AS a
INNER JOIN team AS b
WHERE a.name < b.name;

The question is: I saw the SQL SYNTAX which works out pretty good, but i can't figure out how it works. Anyone could help? thx.

This SQL SYNTAX is below:

SELECT a.name, b.name
from team a, team b 
where a.name < b.name;

`SELECT * FROM A, B ... WHERE ` is *synonym* for `SELECT * FROM A JOIN B ON ()` ;) — xerx593, May 05 '18 at 09:00
You saw archaic SQL syntax -- as if you were reading Shakespeare and started to talk like his characters because you saw the words written down. Joins are correctly written using standard, explicit, proper `JOIN` syntax, not with commas in the `FROM` clause. — Gordon Linoff, May 05 '18 at 10:41

score 1 · Accepted Answer · answered May 05 '18 at 09:00

1

These queries are just different ways to write the same thing. The first is ANSI-89 join syntax, the second ANSI-92 join syntax. The newer syntax is preferred because it keeps join conditions closer to the joined table, especially for multiple joins.

answered May 05 '18 at 09:00

Andomar

Thx. I'd better with New set operations UNION JOIN. – Sean.H May 05 '18 at 10:23

1 Answers1