SQL Query to count number of records must match total number of records - sql

Question

I have 2 tables as
Result Master
+------+-------------+
| QnID | Description |
+------+-------------+
| 1 | Qn1 |
| 2 | Qn2 |
| 3 | Qn3 |
| 4 | Qn4 |
| 5 | Qn5 |
+------+-------------+
Result Details
+----+------+--------+--------+
| ID | QnID | TCDesc | Result |
+----+------+--------+--------+
| 1 | 1 | TC1 | PASS |
| 2 | 1 | TC2 | FAIL |
| 3 | 1 | TC3 | PASS |
| 4 | 2 | TC1 | PASS |
| 5 | 3 | TC1 | PASS |
| 6 | 3 | TC1 | PASS |
| 7 | 3 | TC3 | PASS |
+----+------+--------+--------+
I need a query which will return following result:
+----+------+--------+
| ID | QnID | Result |
+----+------+--------+
| 1 | 2 | PASS |
| 2 | 3 | PASS |
| 3 | 4 | ERROR |
| 4 | 5 | ERROR |
+----+------+--------+
Conditions:
each question will have different number of testcase "ResultDetails", I need to select questions for which all the test case get passsed (number of entries for a particular question must be same as number of test cases passed for the same) or Error (ResultDetail doesn't have an entry for a question).
Can anyone please help me with a query, thank you.

Answer 1

You can get the desired results using a common table expression and conditional aggregation.
First, create and populate sample tables (Please save us this step in your future questions):
DECLARE #ResultMaster AS TABLE
(
QnID int,
Description char(3)
);
INSERT INTO #ResultMaster (QnID, Description) VALUES
(1, 'Qn1'),
(2, 'Qn2'),
(3, 'Qn3'),
(4, 'Qn4'),
(5, 'Qn5');
DECLARE #ResultDetails AS TABLE
(
ID int,
QnID int,
TCDesc char(3),
Result char(4)
);
INSERT INTO #ResultDetails VALUES
(1, 1, 'TC1', 'PASS'),
(2, 1, 'TC2', 'FAIL'),
(3, 1, 'TC3', 'PASS'),
(4, 2, 'TC1', 'PASS'),
(5, 3, 'TC1', 'PASS'),
(6, 3, 'TC1', 'PASS'),
(7, 3, 'TC3', 'PASS');
Then, use a common table expression to calculate the number of pass details and a simple count to get the number of total details:
WITH CTE AS
(
SELECT M.QnId,
COUNT(CASE WHEN Result = 'PASS' THEN 1 END) As CountPass,
COUNT(Result) As CountDetails
FROM #ResultMaster As M
LEFT JOIN #ResultDetails As D ON M.QnId = D.QnId
GROUP BY M.QnId
)
Then, select from that cte:
SELECT ROW_NUMBER() OVER(ORDER BY QnId) AS Id,
QnId,
CASE WHEN CountDetails = 0 THEN
'ERROR'
ELSE
'PASS'
END
FROM CTE
WHERE CountPass = CountDetails
Results:
+----+------+--------+
| ID | QnID | Result |
+----+------+--------+
| 1 | 2 | PASS |
| 2 | 3 | PASS |
| 3 | 4 | ERROR |
| 4 | 5 | ERROR |
+----+------+--------+
You can see a live demo on rextester.