sql ON DUPLICATE KEY UPDATE code example

Example 1: mysql insert on dupèlicate

INSERT INTO table_name(c1)
VALUES(c1)
ON DUPLICATE KEY UPDATE c1 = VALUES(c1) + 1;

Example 2: sql get rows with duplicate values

/* Gets reps */
SELECT fieldA, COUNT(*)
FROM tableA
GROUP BY fieldA
HAVING COUNT(*) > 1

/* Use reps to filter results */
SELECT a.*
FROM tableA a
JOIN (
	SELECT fieldA, COUNT(*) as 'count'
	FROM tableA
	GROUP BY fieldA
	HAVING COUNT(*) > 1
) b
ON a.fieldA = b.fieldA

Example 3: mysql on duplicate key update

INSERT INTO t1 (a,b,c) VALUES (1,2,3)
  ON DUPLICATE KEY UPDATE c=3;
INSERT INTO t1 (a,b,c) VALUES (4,5,6)
  ON DUPLICATE KEY UPDATE c=9;

Example 4: sql insert or update

-- Oracle: Example for Insert or update in t1 from t2 values 
MERGE INTO table1 t1
USING table2 t2
ON (t1.CODE = t2.ID)
WHEN MATCHED THEN
    UPDATE SET t1.COL1 = t2.VALUE1
WHEN NOT MATCHED THEN
    INSERT (CODE, COL1)  VALUES (t2.ID, t2.VALUE1);

-- MySql (makes a INSERT + DELETE if existing)
REPLACE INTO table1 (pk_id, col1) VALUES (5, 'aaaa');
--
INSERT INTO table1 VALUES (key, generation)
ON DUPLICATE KEY UPDATE (key = key, generation = generation + 1);

Example 5: mysql on duplicate key update

UPDATE t1 SET c=c+1 WHERE a=1 OR b=2 LIMIT 1;