SQL Server - highlight sequence of rows with specific conditions [closed] - sql

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From my query I get:
----------
| Val | Avg |
----------
| 1 | 7 |
----------
| 5 | 7 |
----------
| 2 | 7 |
----------
| 5 | 7 |
----------
| 6 | 7 |
----------
| 5 | 7 |
Assume the above is in some table "t". I want to check if there are three or more rows where the value is less then the corresponding average. If there are three or more points that satisfy that condition then they should be highlighted in a result like this:
----------
| Val | Avg | BelowAvg |
----------
| 8 | 7 | 0 |
----------
| 7 | 7 | 0 |
----------
| 9 | 7 | 0 |
----------
| 5 | 7 | 1 |
----------
| 6 | 7 | 1 |
----------
| 5 | 7 | 1 |
Any suggestions?

Answer 1

This works with your previous data. A problem will arise when you will have the same average for another set of VAL:
SQL Fiddle
MS SQL Server 2012 Schema Setup:
CREATE TABLE t
([Val] int, [Avg] int)
;
INSERT INTO t
([Val], [Avg])
VALUES
(1, 3),
(5, 3),
(2, 3),
(5, 7),
(6, 7),
(5, 7)
;
Query 1:
SELECT t.*,
CASE WHEN t2.cnt >= 3 THEN 1 ELSE 0 END as BelowAvg
FROM t
LEFT OUTER JOIN (SELECT avg, count(*) as cnt
FROM t
WHERE val < avg
GROUP BY avg) t2 ON t.avg = t2.avg
Results:
| VAL | AVG | BELOWAVG |
|-----|-----|----------|
| 1 | 3 | 0 |
| 5 | 3 | 0 |
| 2 | 3 | 0 |
| 5 | 7 | 1 |
| 6 | 7 | 1 |
| 5 | 7 | 1 |
EDIT: Assuming that this is related to a question, you can have something like this :
SQL Fiddle
MS SQL Server 2012 Schema Setup:
CREATE TABLE t
([QuestionID] int, [Val] int, [Avg] int)
;
INSERT INTO t
([QuestionID], [Val], [Avg])
VALUES
(1, 1, 3),
(1, 5, 3),
(1, 2, 3),
(2, 5, 7),
(2, 6, 7),
(2, 5, 7)
;
Query 1:
SELECT t.*,
CASE WHEN t2.cnt >= 3 THEN 1 ELSE 0 END as BelowAvg
FROM t
LEFT OUTER JOIN (SELECT QuestionID, count(*) as cnt
FROM t
WHERE val < avg
GROUP BY QuestionID) t2 ON t.QuestionID = t2.QuestionID
Results:
| QUESTIONID | VAL | AVG | BELOWAVG |
|------------|-----|-----|----------|
| 1 | 1 | 3 | 0 |
| 1 | 5 | 3 | 0 |
| 1 | 2 | 3 | 0 |
| 2 | 5 | 7 | 1 |
| 2 | 6 | 7 | 1 |
| 2 | 5 | 7 | 1 |