mysql on duplicate 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: select where duplicate mysql

SELECT 
    col1, COUNT(col1),
    col2, COUNT(col2)
FROM
    table_name
GROUP BY 
    col1, 
    col2
HAVING 
       (COUNT(col1) > 1) AND 
       (COUNT(col2) > 1);

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: mysql find duplicates in same table

## Find ALL duplicate recods by value (without grouping them by value) ##
# to find the duplicate, 
# replace all instances of tableName with your table name
# and all instances of duplicateField with the field name where you look for duplicates
SELECT t1.*
FROM tableName AS t1
INNER JOIN(
	SELECT duplicateField
	FROM tableName
	GROUP BY duplicateField
	HAVING COUNT(duplicateField) > 1
)temp ON t1.duplicateField = temp.duplicateField
order by duplicateField

Example 5: mysql on duplicate key ignore

INSERT INTO table_tags (tag) VALUES ('tag_a'),('tab_b'),('tag_c') ON DUPLICATE KEY UPDATE tag=tag;

Example 6: mysql on duplicate key update

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