从多个表合并这些mysql查询

Question

Let say I have a table with a list of users, and I retrieve the users table like this:

SELECT userid FROM users WHERE year = 2012

That generates a list of users, more specifically, userid's (digits).

So, lets say our list looks like this now (random userids):

1234
9532
0983
2098
1980

In other table, we have the users favorite colors, one entry for each color. So user 1234 could have multiple entries in the table (lets call it fav_colors):

1234 red
1234 blue
9532 yellow
9532 red
0983 blue
0983 purple

This is very simplified example of a concept I am trying to grasp. How can I form one query to show me the users where the year is 2012 (from the first query), and who likes the color red? I am having trouble combining the queries from the users table and the fav_colors table

Thanks

Answer 1

This should get you the results you're looking for

SELECT u.userid, c.color
FROM users AS u
JOIN fav_colors AS c
  ON u.userid = c.userid
WHERE u.year = 2012
  AND c.color_name = 'red'

Answer 2

You need to use SQL Joins to link both tables and use a where clause for the year and the red color.

See : http://www.w3schools.com/sql/sql_join.asp for more info on SQL Joins.

Tell me if you need more explanations.