mysql - order by frequency with multiple columns

I have a table with 5 columns:

• tag 1
• tag 2
• tag 3
• tag 4
• tag 5

If I want to show result开发者_StackOverflow中文版s ordered by the popularity(frequency) of those tags, what kind of query would i use?

Because the table isn't normalized, you'll have to flatten it first:

SELECT a.column, a.tag1 AS tag
  FROM TABLE a
UNION ALL
SELECT b.column, b.tag2
  FROM TABLE b
UNION ALL
SELECT c.column, c.tag3
  FROM TABLE c      
UNION ALL
SELECT d.column, d.tag4
  FROM TABLE d
UNION ALL
SELECT e.column, e.tag5
  FROM TABLE e

...before you can count them:

SELECT t.tag, COUNT(*) tag_popularity
  FROM (SELECT a.column, a.tag1 AS tag
          FROM TABLE a
        UNION ALL
        SELECT b.column, b.tag2
          FROM TABLE b
        UNION ALL
        SELECT c.column, c.tag3
          FROM TABLE c      
        UNION ALL
        SELECT d.column, d.tag4
          FROM TABLE d
        UNION ALL
        SELECT e.column, e.tag5
          FROM TABLE e) x
GROUP BY x.tag
ORDER BY tag_popularity DESC