SQL查询按COUNT过滤

Question

I have two tables: comments and regions. The sql query is:

SELECT comments.region, 
    COUNT(comments.region)
FROM comments, regions
WHERE comments.region = regions.id
GROUP BY comments.region;

The result table is (id, COUNT(comments.region)):

1 | 3       
2 | 1
3 | 7
4 | 6
5 | 2

How I can add rule to filter all rows where COUNT(comments.region) > 5? Finally I need to get a summary table:

3 | 7
4 | 6

Answer 1

Use HAVING :

SELECT c.region, COUNT(*)
FROM comments c
INNER JOIN regions r
    ON c.region = r.id
GROUP BY c.region
HAVING COUNT(*) > 5

Notes:

I replaced your implicit join with an explicit INNER JOIN using an ON clause. As @GordonLinoff likes to say, you should avoid putting commas into the WHERE clause. I also introduced table aliases into the query, which relieve us from having to write the full table name repeatedly.

Answer 2

Are you looking for HAVING ?

   SELECT comments.region, 
          COUNT(comments.region)
     FROM comments,
          regions
    WHERE comments.region = regions.id -- obsolete syntax: use JOIN instead
 GROUP BY comments.region
   HAVING COUNT(comments.region) > 5;

Answer 3

You have to use the HAVING clause

SELECT comments.region, COUNT(comments.region)
  FROM comments, regions
  WHERE comments.region = regions.id
  GROUP BY comments.region
  HAVING COUNT(comments.region) > 5;

See here for more details on HAVING clause https://www.w3schools.com/sql/sql_having.asp