SQL - IF EXISTS UPDATE ELSE INSERT [duplicate]

Question

This question already has answers here:

How do I update if exists, insert if not (AKA "upsert" or "merge") in MySQL? (2 answers)

Closed 9 years ago.

I have the following query:

INSERT INTO distance (deviceID,datum,tavolsag)
 SELECT 
deviceID, DATE(FROM_UNIXTIME(timestamp)) as datum, 
sum(case when distanceKM/1000<416 then distanceKM/1000 else 0 end) as tavolsag
FROM eventdata 
GROUP BY datum,deviceID;

I would like to know how can avoid data duplication when I run the query on daily basis/ or use the "if exists update else insert" method.

Thx

Answer 1

If you have a UNIQUE constraint on (deviceID, datum), then you can use INSERT ... ON DUPLICATE KEY

INSERT INTO distance (deviceID, datum, tavolsag)
SELECT d.deviceID
     , DATE(FROM_UNIXTIME(d.timestamp)) as datum
     , SUM(CASE WHEN d.distanceKM/1000<416 
                THEN d.distanceKM/1000
                ELSE 0 END
       ) AS tavolsag 
  FROM eventdata d
 GROUP BY datum, deviceID
ON DUPLICATE KEY
UPDATE tavolsag = VALUES(tavolsag)

When this statement is executed, this will attempt the insert, and if the inserting would violate a unique key constraint, rather than throw an error, MySQL will execute an UPDATE instead, equivalent to:

UPDATE distance
   SET tavolsag  = ?
 WHERE device_id = ?
   AND datum     = ?

---

If there are multiple unique constraints, then the action depends on which unique constraint is flagged as being violated. The actual update that is performed will be relative to the unique constraint that would have thrown the error.

Answer 2

try this :

 INSERT INTO distance (deviceID,datum,tavolsag)
 SELECT deviceID,datum,tavolsag from(select 
deviceID, DATE(FROM_UNIXTIME(timestamp)) as datum, 
sum(case when distanceKM/1000<416 then distanceKM/1000 else 0 end) as tavolsag
FROM eventdata 
GROUP BY datum,deviceID)t
on duplicate key update set datum=......, tavolsag = .....