我遇到了一个场景，它给了我一个空错误，不知道如何解决它 - 甚至无法弄清楚null错误在哪里抛出。
CREATE PROCEDURE reportFreeCooling(
IN fromDate VARCHAR (50),
IN toDate VARCHAR (50),
IN timeZone VARCHAR (50)
)
BEGIN
DECLARE startDate VARCHAR (50);
DECLARE endDate VARCHAR (50);
DECLARE startDateOriginal VARCHAR (50);
DECLARE mylogID INT;
DECLARE myItemId varchar (50);
DECLARE myItemId2 varchar (50);
DECLARE xHours varchar (50);
DECLARE endHoursNull varchar(50);
DECLARE endHoursNotNull varchar (50);
DECLARE firstRow INT;
DECLARE firstRowDate varchar(50);
DECLARE minRowDate varchar (50);
DECLARE minRow int;
SET startDate = FROM_UNIXTIME(fromDate/1000);
SET endDate = FROM_UNIXTIME(toDate/1000);
SET startDateOriginal = FROM_UNIXTIME(fromDate/1000);
SET mylogID = (SELECT logID FROM logs WHERE details LIKE 'FCT%' LIMIT 1);
SET myItemID = (SELECT i.itemId FROM items i WHERE i.name LIKE '%KW PRE%');
SET myItemID2 = (SELECT i.itemId FROM items i WHERE i.name LIKE '%KW STA%');
DROP TABLE IF EXISTS tempTable3 CASCADE;
SET @sql = NULL;
SET @sql = CONCAT(
'CREATE TEMPORARY TABLE tempTable3 AS (SELECT
@row := @row + 1 AS rownum,
a.logId,a.name AS Type,
L1.recordId,
L2.recordId AS next_recordId,
L1.completed,
L2.completed AS next_completed,
L3.completed AS first_completed,
L1.activityId AS activityJoin,
L2.activityId AS next_activityId,
IF(L1.activityId = L2.activityId, 1, NULL) AS isError,
CASE
when a.name LIKE ''%Enable%'' THEN time_to_sec(timediff(L2.completed, L1.completed)) / 3600
ELSE NULL
END AS coolingHours,
TO_SECONDS(L2.completed) - TO_SECONDS(L1.completed) AS timeInSeconds,
((SUBSTR(l.details, INSTR(l.details, '':'') + 1))) AS charge,
time_to_sec(timediff(''', endDate, ''', ''', startDate, ''')) / 3600 AS totalTimeRange,
CONVERT_TZ(''', startDate, ''', ''UTC'', ''', timeZone, ''') AS startingDate,
CONVERT_TZ(''', endDate, ''', ''UTC'', ''', timeZone, ''') AS endingDate,
(L1.item', myItemID, ' - L1.item', myItemID2, ') AS itemDifference,
((L1.item', myItemID, ' - L1.item', myItemID2, ') *
(TIME_TO_SEC(TIMEDIFF(L2.completed, L1.completed))/3600)) AS kwDifference,
((L1.item', myItemID, ' - L1.item', myItemID2, ') * (SUBSTR(l.details, INSTR(l.details, '':'') + 1))) AS cost,
((((L1.item', myItemID, ' - L1.item', myItemID2, ') * (SUBSTR(l.details, INSTR(l.details,'':'') + 1)))
* (TIME_TO_SEC(TIMEDIFF(L2.completed, L1.completed)) / 3600))) AS costT,
DATABASE() AS databaseName, i.itemId ,l.details
FROM
(SELECT @row:=0)R,
(SELECT T1.completed
, (SELECT MIN(T2.completed)
FROM log',mylogID, ' T2
WHERE T2.completed > T1.completed) AS next_completed
, (SELECT MAX(T2.completed)
FROM log',mylogID, ' T2
WHERE T2.completed < T1.completed) AS frst_completed
FROM log',mylogID, ' T1
ORDER BY T1.completed
)TimeOrder
LEFT JOIN log', mylogID, ' L1 ON (L1.completed = TimeOrder.completed)
LEFT JOIN log', mylogID, ' L2 ON (L2.completed = TimeOrder.next_completed)
LEFT JOIN log', mylogID, ' L3 ON (L3.completed = TimeOrder.frst_completed)
LEFT JOIN activities a ON L1.activityId = a.activityId
LEFT JOIN logs l ON a.logId = l.logId
LEFT JOIN items i ON l.logId = i.logId AND i.name LIKE ''%KW PRE%''
)order by L1.completed');
PREPARE stmt FROM @sql;
EXECUTE stmt;
DEALLOCATE PREPARE stmt;
/* sets next row hours when date is after startdate and first is null */
SET @startDate = (SELECT MIN(completed) FROM tempTable3 WHERE coolingHours is NULL AND
completed BETWEEN startDate AND endDate);
SET @startDate2 = (SELECT MAX(completed) FROM tempTable3 WHERE completed < @startDate);
SET startDate = @startDate2;
/* sets end hours when last row is enabled and next_completed is greater than end date */
SET @endHoursNotNull = (SELECT MAX(completed) AS maxCompletedDateAndCoolingHoursNotNull FROM tempTable3 WHERE coolingHours is NOT NULL AND
completed BETWEEN startDate AND endDate);
SET endHoursNotNull= @endHoursNotNull;
SET @endHoursNull = (SELECT MAX(completed) AS maxCompletedAndCoolingHoursNull FROM tempTable3 WHERE coolingHours is NULL AND
completed BETWEEN startDate AND endDate);
SET endHoursNull = @endHoursNull;
/* sets first row hours when date is after startdate and first enabled */
SET firstRowDate = (SELECT MIN(completed) FROM tempTable3);
IF firstRowDate > startDateOriginal THEN SET startDateOriginal = firstRowDate; END IF;
SET @newcoolingHours = (SELECT (time_to_sec(timediff(next_completed, startDateOriginal)) / 3600) AS newCoolingHours
FROM tempTable3 WHERE completed >= startDateOriginal
AND completed BETWEEN startDate AND endDate LIMIT 1);
SET xHours = @newCoolingHours;
SET minRowDate = (SELECT MIN(completed) FROM tempTable3 WHERE completed BETWEEN startDate AND endDate LIMIT 1 );
SET minRow = (SELECT MIN(rowNum)FROM tempTable3 WHERE completed BETWEEN startDate AND endDate LIMIT 1 );
/* set first row number and hours for when first row in log(itemId) is greater then startdate */
SET @sqlTemp = NULL;
SET @sqlTemp =
CONCAT(
'SELECT rowNum,l.completed,l.next_completed,l.first_completed,startingDate,endingDate,Type,itemDifference,
''',startDateOriginal,''' AS oStartDate, ''',startDate,''' as startDate,
(time_to_sec(timediff(next_completed, completed)) / 3600)AS cHours,
CASE
WHEN (''',startDateOriginal,''' > ''',startDate,''' AND Type LIKE ''%Enable%'' AND rowNum = ''',minRow,''')
THEN (time_to_sec(timediff(next_completed, ''',startDateOriginal,''')) / 3600)
WHEN (DAYOFYEAR(completed) = DAYOFYEAR(''',startDate,'''))
THEN ''',xHours,'''
WHEN (''',endHoursNotNull,''' > ''',endHoursNull,''' AND next_completed > ''',endDate,''' )
THEN ((time_to_sec(timediff(''',endDate,''', completed))) / 3600)
ELSE coolingHours
END AS coolingHours,
isError,charge,totalTimeRange,
l.logId,databaseName,i.name,l.itemId,
CASE
WHEN (''',startDateOriginal,''' > ''',startDate,''' AND Type LIKE ''%Enable%'' AND rowNum = ''',minRow,''')
THEN (itemDifference*(time_to_sec(timediff(next_completed, ''',startDateOriginal,''')) / 3600))
WHEN (DAYOFYEAR(completed) = DAYOFYEAR(''',startDate,'''))
THEN (''',xHours,'''* itemDifference)
WHEN (''',endHoursNotNull,''' > ''',endHoursNull,''' AND next_completed > ''',endDate,''' )
THEN (itemDifference*((time_to_sec(timediff(''',endDate,''', completed))) / 3600))
ELSE kwDifference
END AS kwDifference,cost,
CASE
WHEN (''',startDateOriginal,''' > ''',startDate,''' AND Type LIKE ''%Enable%'' AND rowNum = ''',minRow,''')
THEN ((time_to_sec(timediff(next_completed, ''',startDateOriginal,''')) / 3600)* cost)
WHEN (DAYOFYEAR(completed) = DAYOFYEAR(''',startDate,'''))
THEN (''',xHours,''' * cost)
WHEN (''',endHoursNotNull,''' > ''',endHoursNull,''' AND next_completed > ''',endDate,''' )
THEN (((time_to_sec(timediff(''',endDate,''', completed))) / 3600) * cost)
ELSE costT
END AS costT,l.details,timeInSeconds
FROM tempTable3 l
inner join items i ON l.logId = i.logId AND i.name LIKE ''%KW PRE%''
WHERE l.itemId = ''',myItemId,'''
AND completed BETWEEN ''', startDate, ''' AND ''', endDate, '''
');
PREPARE stmtTemp FROM @sqlTemp;
EXECUTE stmtTemp;
DEALLOCATE PREPARE stmtTemp;
DROP TEMPORARY TABLE tempTable3;
END //
DELIMITER ;
我知道这与最后一行数据有关，而next_completed为null
最后一行数据
row Num completed next_completed first_completed starting Date ending Date
28 12/28/2013 6:30:35 PM 12/29/2013 12:07:19 AM 12/27/2013 11:22:54 PM 12/31/1969 10:00:00 PM 12/31/2013 10:00:00 PM
29 12/29/2013 12:07:19 AM 12/29/2013 8:56:58 AM 12/28/2013 6:30:35 PM 12/31/1969 10:00:00 PM 12/31/2013 10:00:00 PM
30 12/29/2013 8:56:58 AM 12/31/2013 11:27:40 PM 12/29/2013 12:07:19 AM 12/31/1969 10:00:00 PM 12/31/2013 10:00:00 PM
31 12/31/2013 11:27:40 PM (null) 12/29/2013 8:56:58 AM 12/31/1969 10:00:00 PM 12/31/2013 10:00:00 PM