limiting the rows to where the sum a column equals a certain value in MySQL

Question

I want to write a query which returns all rows until the sum of one of the columns value reaches a certain value.

For example in the table below:

Answer 1

Here's a way to do it without a stored procedure:

SET @msum := 0;
SELECT t1.* 
FROM (
    SELECT m.*,  
          (@msum := @msum + m.meetings) AS cumulative_meetings
    FROM meetings m 
    ORDER BY m.date ASC
) t1 
WHERE t1.cumulative_meetings <= 7;

Answer 2

Hemant you do not state the RDBMS that use. Here is a script in t-sql that you can use in order to solve your problem.

DECLARE @numberToReach INT;
SET @numberToReach = 10; --you can change this

DECLARE @date DATETIME;
DECLARE @etc VARCHAR(20);
DECLARE @meeting INT;
DECLARE @temp_sum INT;

CREATE TABLE #tempTable
    (
        Dates DATETIME,
        Etcs VARCHAR(20),
        Meeting INT,
    )

DECLARE tempcursor CURSOR FOR
        SELECT *
        FROM YourTABLENAME
OPEN tempcursor;
FETCH NEXT FROM tempcursor INTO @date, @etc, @meeting;

WHILE(@@FETCH_STATUS = 0)
BEGIN
    SET @temp_sum = @temp_sum + @meeting;
    IF @temp_sum < @numberToReach 
    BEGIN
        INSERT INTO #tempTable
        (
            Dates,
            Etcs,
            Meeting
        )
        VALUES
        (
            @date, 
            @etc, 
            @meeting
        )

        FETCH NEXT FROM tempcursor INTO @date, @etc, @meeting;
    END 
END

SELECT * FROM #tempTable

CLOSE tempcursor
DEALLOCATE tempcursor

DROP TABLE  #tempTable

Answer 3

If you are using SQL Server, then use CROSS APPLY.

Answer 4

In Oracle, I think you can use the SUM analytic function. You can refer here: http://www.adp-gmbh.ch/ora/sql/analytical/sum.html

Answer 5

Here's an ugly way:

SELECT *
FROM meetings m1
WHERE (SELECT SUM(m2.Meeting) 
       FROM meetings m2 
       WHERE m2.DATE < m1.DATE OR (m2.DATE = m1.DATE AND m2.ETC >= m1.ETC)) <= 7

The ordering is based on DATE first, then ETC in descending order, since that seems to be what we have to go on. Note that if that is not unique, you will get the wrong result.

Answer 6

This one outperforms all.

SET @runningTotal=0;
SELECT
  O.Id,
  O.Type,
  O.MyAmountCol,
  @runningTotal + O.MyAmountCol as 'RunningTotal',
  @runningTotal := @runningTotal + O.MyAmountCol
FROM Table1 O
HAVING RunningTotal <=7;

SQL Fiddle

Take a look at execution plans for both queries.