The Big Programming Thread - Page 382

On October 27 2013 14:37 obesechicken13 wrote:

Show nested quote +

On October 27 2013 14:08 WolfintheSheep wrote:

On October 27 2013 13:47 obesechicken13 wrote:
Having some difficulty with database homework problems. I'm trying to find a highest average rating for something (let's assume movies, but it's really wine).

But I'm trying to find it by the country. So I want to return the highest rated wine from Canada and Mexico and China at the same time with no extras. I'm not allowed to list the second lowest below.

Is this supposed to be in SQL? If so, it should be fairly easy if you look through the API. Depending on how the database is setup, and the constraints on the question, you might have to do some annoying JOINs and have a very bloated query.

Yeah, I think I'm getting it. Very bloated indeed but it forces me to use some of the stuff in class.

Here's something that's messing me up. I need to be able to get only the avg_rate column in order to do a comparison and find a max value. Unless having allows you to compare on a single element and not a grouping like where does (brb have to try this)


This query returns fine


Why is everything 0s?

I'm running postgresql latest in a gui environment and the gui compiler seems a bit buggy (I can't use doublequotes) so maybe that's the problem.

SELECT
  MAX(avg_rating)
FROM
    countries c2
    INNER JOIN
    winemakers wm2
      ON c2.id = wm2.cid
    INNER JOIN
    (
      SELECT
        wid,
        avg(rating) AS avg_rate
      FROM
          wine w2 NATURAL JOIN
          ratings r2
      GROUP BY wid
    ) AS avg_ratings
      ON avg_ratings.wid = wm2.wid
GROUP BY cid

SELECT avg(sum) AS avg
FROM numbers
HAVING avg > 5

SELECT *
FROM
(
SELECT avg(sum) AS avg
FROM numbers
) 
WHERE avg > 5

	public void printArray() {
		for (int i = 0; i < this.grid.length; i++) {
			for (int j = 0; j < this.grid.length; j++) {
				System.out.printf("%d ", this.grid[i][j]);
			}
			System.out.println();
		}
	}

	public void printArray(int row) {
		if (row == this.grid.length) {
			return;
		}
		else {
			for (int i = 0; i < this.grid.length; i++) {
				System.out.printf("%d ", this.grid[row][i]);
			}
			System.out.println();
			printArray(row + 1);
		}
	}