Question

Using SQL Server 2005

I have a table with the following columns

id
name
date
value

I would like to select all rows from the table where there are not four consecutive zeroes by date. How would I do that? Below is an example of what I mean.

id      name     date         value
1       a        1/1/2010     5
2       a        1/2/2010     3
3       a        1/3/2010     5
4       a        1/4/2010     0
5       a        1/7/2010     0
6       a        1/8/2010     0
7       a        1/9/2010     2
8       a        1/10/2010    3
9       a        1/11/2010    0
10      a        1/15/2010    0
11      a        1/16/2010    0
12      a        1/17/2010    0
13      a        1/20/2010    4
14      a        1/21/2010    4

I would like the result of the query to include all rows except id 9-12.

Answer 1

This is assuming you ordered the rows by ID but you can simply change the ORDER BY id to something else and it should still work.

Using the T-SQL CTE found on this Kodyaz Development Resources site I was able to create the below code. I have it working so it deletes the rows where there are two consecutive zeroes, not 4, as I tested it on my code and just changed the table/row names.

WITH CTE as (
  SELECT
    RN = ROW_NUMBER() OVER (ORDER BY id),
    *
  FROM tablename
)
SELECT
  [Current Row].*
FROM CTE [Current Row]
LEFT JOIN CTE [Previous Row] ON
  [Previous Row].RN = [Current Row].RN - 1
LEFT JOIN CTE [Next Row] ON
  [Next Row].RN = [Current Row].RN + 1
WHERE
  not([Current Row].value = 0 AND [Next Row].value = 0) AND  
     // this deletes the row where value is zero and the next rows value is zero
  not([Previous Row].value = 0 AND [Current Row].value = 0) 
     // this deletes the row where value is zero and the previous rows value is zero

All you have to do to make it work for your case is putting each possible combination within the WHERE statement. For example dealing with this row and the 3 next rows equaling 0 OR this row the previous and the 2 next rows.