Count multiple results in MySQL query

Question

Basically what I have is a ratings system. 1-5 stars for 4 categories. What I'm trying to do is get a count of the results for each category. For instance:

  Category 1: 20 1 star, 32 2 star, 40 3 star, 35 4 star, 19 5 star
  ...
  Category 4: 10 1 star, 12 2 star, 45 3 star, 54 4 star, 2 5 star

I know that I can just do 20 queries, ( SELECT COUNT(*) WHERE BizID=$id AND category1=1 / SELECT COUNT(*) WHERE BizID=$id AND category1=2 ...), but I was wondering if there was a more efficient way. Seems like if I had a large number of hits, or there were a huge number of ratings, the script would bog down pretty bad at this point. Any help would be appreciated.

Table Structure
RateID - int(10)
UserID - varchar(8)
BizID - varchar(8)
Cat1 - int(1)
Cat2 - int(1)
Cat3 - int(1)
Cat4 - int(1)
Date - int(10)

Answer 1

You can get counts by Category and the Star rating in one shot using the CASE statement, as below:

SELECT
    SUM
    (
        CASE
            WHEN Cat1 = 1 THEN 1
            ELSE 0
        END
    ) Cat1_1,
    SUM
    (
        CASE
            WHEN Cat1 = 2 THEN 1
            ELSE 0
        END
    ) Cat1_2,
    SUM
    (
        CASE
            WHEN Cat1 = 3 THEN 1
            ELSE 0
        END
    ) Cat1_3,
    SUM
    (
        CASE
            WHEN Cat1 = 4 THEN 1
            ELSE 0
        END
    ) Cat1_4,
    SUM
    (
        CASE
            WHEN Cat1 = 5 THEN 1
            ELSE 0
        END
    ) Cat1_5,
    SUM
    (
        CASE
            WHEN Cat2 = 1 THEN 1
            ELSE 0
        END
    ) Cat2_1,
...
...
... 
FROM mytable
WHERE BizID=$id;

Answer 2

Try with this:

<?php
$sql = "SELECT COUNT(BizID) WHERE BizID = " . $id . " AND category1 IN (1, 2, 3, 4, ...)";