Conditionals can be done by means of the CASE operator/expression:

Your query will work with:

SELECT 
    ts, 
    (CASE WHEN column_5 > 0 
     THEN
        0              /* We are ignoring column_1 */
     ELSE
        column_1       /* We are using its value */
     END) + column_2 + column_3 + column_4 AS total
FROM
    t
ORDER BY 
    ts ;

You can check it at http://rextester.com/IHM39024

The CASE expression is standard SQL.

MySQL also offers an IF function that could be used in this case. In fact IF(a,b,c) = CASE WHEN a THEN b ELSE c END.

You can also put the sum inside a case statement, where the case evaluates the other condition, and then only sum thoses records where the condition is true...

  SELECT m.member_id, m.teamname, 
    Sum(Case When r.track_Id = '$chosentrack' 
         Then total_points Else 0 End) TotalChosenTrackPoints,
    Sum(Case When r.track_Id < '$chosentrack' 
         Then total_points Else 0 End) TotalLessThanChosenTrackPoints, 
    total_points as last_race_points  
 FROM members m
    Join members_leagues l
       On l.member_id = m.member_id  
    Join member_results r
       On r.member_id = m.member_id
 Where l.league_id = '$chosenleague'
    And l.start_race = '$chosentrack'
 Group By m.member_id
 Order By r.total_points Desc, 
     last_race_points  Desc, m.TeamName Desc  

In mysql we can make use of case statement something like this

select SUM(CASE WHEN Status = 'PAID OFF' THEN Price ELSE Price/2 END) as total where date(DatePaid) = CURDATE()

But the table design is not so good to perform these kind of aggregate functions. Especially the status column.

You just want conditional aggregation, if I understand correctly:

SELECT SUM(CASE WHEN ce_type = 'IN' or ce_type is NULL then payment_amount
                WHEN ce_type = 'OUT' then - payment_amount
           END) as payment_amount
FROM customer_payment_options
WHERE real_account_id = '11' AND real_account_type = 'HQ' AND company_id = '1';

Try with a CASE in this way :

SUM(CASE 
    WHEN PaymentType = "credit card" 
    THEN TotalAmount 
    ELSE 0 
END) AS CreditCardTotal,

Should give what you are looking for ...

Change this:

SUM(btc_total WHERE order_type = 'BUY') AS buy_total

to this:

SUM(IF(order_type='BUY',btc_total,NULL)) AS buy_total

The MySQL IF() function evaluates the first argument as a boolean, if that's TRUE, it returns the second argument, else it returns the third argument.

The IF() will be evaluated for each row, and the return from that expression will get totaled up by the SUM() aggregate.

or, use the more ANSI-standard equivalent to achieve the same result:

SUM(CASE WHEN order_type = 'BUY' THEN btc_total END) AS buy_total

This pattern is commonly referred to as "conditional aggregation".

For the "counts" we can replace COUNT with SUM, like this:

SUM(order_type = 'BUY') AS buy_fill

MySQL evaluates the equality comparison as a boolean, which returns 1, 0 or NULL, which are then totaled up by the SUM aggregate. (A COUNT of that would include zeros and ones, not just the ones.)

The above is equivalent to

SUM( CASE
     WHEN order_type  = 'BUY' THEN 1
     WHEN order_type <> 'BUY' THEN 0
     ELSE NULL
     END
   ) AS buy_fill

If we want to use a COUNT aggregate, we could do it like this:

COUNT(IF(order_type = 'Buy',1,NULL)) AS buy_fill

(We could use any non-null value in place of 1, and get an equivalent result.)

Try this query:

SELECT
   SUM(CASE WHEN Status = 'pending' THEN Amount ELSE 0 END) AS Pending
  ,SUM(CASE WHEN Status = 'Success' THEN Amount ELSE 0 END) AS Success
  ,SUM(CASE WHEN Status = 'Failure' THEN Amount ELSE 0 END) AS Failure
FROM MyTable

You can also use this dynamic query:

SET @sql = NULL;
SELECT
  GROUP_CONCAT(DISTINCT
    CONCAT(
      'SUM(CASE WHEN `Status` = ''',
      `Status`,
      ''' THEN Amount ELSE 0 END) AS `',
      `Status`, '`'
    )
  ) INTO @sql
FROM MyTable;

SET @sql = CONCAT('SELECT ', @sql,'
                     FROM MyTable
                  ');

PREPARE stmt FROM @sql;
EXECUTE stmt;
DEALLOCATE PREPARE stmt;

See this SQLFiddle

You need to have a subquery that gives you all codes that have at least 1 record where update=1 and you need to join this back to your table and do the group by and sum:

select m.code, sum(total)
from mytable m
inner join (select distinct code from mytable where `to_update`=1) t on m.code=t.code
group by m.code

Or you can sum the to_update column as well and filter in having:

select m.code, sum(total)
from mytable m
group by m.code   
having sum(to_update)> 0