SQL selection based on link field

Question

It seems to me that the idiot is asking about this ...

Table 1: users
id serial
person integer
username char (32)

Table 2: persons
id serial
name char (16)

Can I run a query that returns the field name for persons by specifying the username in Users?

users
1 | 1 | larry123

persons
1 | larry
2 | curly

SQL?

select name from persons where users.person=persons.id and users.username='larry123';

with the desired return

larry

I have been doing this with two passes so far and think that maybe nested selection using join is what I need

1 | larry

0

Stephen Dec 19. '08 at 6:16

1 answer

derobert · Answer 1 · 2008-12-19T06:28:27+0000

It sounds like you are asking how to make a SQL connection:

SELECT
    name
  FROM
    users JOIN persons ON (users.person = persons.id)
  WHERE
    users.username = 'larry123';

this is almost the request you wrote. All you were missing was an offer to join. You can also do it like this:

SELECT name
FROM users, persons
WHERE
      users.person = persons.id
  AND users.username = 'larry123';

I suggest finding a well-written introduction to SQL.