优化MySQL查询以在单个查询中查找用于不同测试的用户的等级

Question

I am using the query to find the rank of a user in a given test id, and this gives me rank for just one test at a time and I have to use foreach to get the test rank of all the test.

SELECT * , t.UserRank
FROM (

SELECT * , (
@rownum := @rownum +1
)UserRank
FROM User_Date_Table, (

SELECT @rownum :=0
)t
WHERE my_test_id  = '$test_id'
ORDER BY test_score DESC
)t
WHERE user_id = '$my_user_id' 

Can a query be generated which can give me user rank for all the test taken by user in single query as this will reduced the db hitting multiple times.

I have to find the all the ranks of user with Test_Type_Id = $my_test_type_id(say), joining a.id with b.my_test_id for a user with user_id = $my_user_id(say)

TABLE STRUCTURE

  My_Test_Table (a)

  id  |  name   |  Test_Type_Id 
  ----------------------------------------------
  1  |  name_1  |  1
  2  |  name_2  |  1    
  3  |  name_3  |  2    
  4  |  name_4  |  1    
  5  |  name_5  |  1
  6  |  name_6  |  2    
  7  |  name_7  |  1    
  8  |  name_8  |  2    
  9  |  name_9  |  1



 User_Date_Table (b)

id  | my_test_id | user_id  | test_score
---------------------------------------------------------
1  | 1  | 32    | 34
2  | 1  | 2     | 345
3  | 2  | 4     | 654
4  | 1  | 76    | 87
5  | 3  | 23    | 453
6  | 2  | 5     | 45
7  | 1  | 43    | 22
8  | 2  | 7     | 987
9  | 2  | 32    | 45
10  | 1     | 1     | 12
11  | 1     | 9 | 35
12  | 3     | 67    | 765
13  | 1     | 88    | 23
14  | 2     | 34    | 76
15  | 3     | 1     | 765
16  | 2     | 54    | 45
17  | 1     | 10    | 87
18  | 1     | 23    | 3
19  | 3     | 44    | 345
20 | 1  | 55    | 232
21  | 2     | 28    | 234
22  | 3     | 32    | 231

Answer 1

Simplest is probably to just remove the user variable for ranking and just do it using a subquery;

SELECT *, (SELECT COUNT(*)+1 
           FROM User_Date_Table b 
           WHERE a.my_test_id = b.my_test_id
             AND a.test_score < b.test_score) userrank
FROM User_Date_Table a
WHERE user_id = '1';

An SQLfiddle to test with.