If I'm inserting data into a table with the following fields:
serialNumber active country
I need to only insert duplicate serialNumbers if active is no.
So for example: I want to insert a record with serialNumber 1234.
If the serial number doesn't already exist in the table go ahead and add it. If it does already exist, check the value of 'active' active is yes then don't add the new record, if it's no then do add the record.
Any ideas how to achieve this in MYSQL?
If the table lacks the necessary unique keys and you do not have permission, or don't want to set the keys you would need, you can use this alternative:
INSERT INTO `table1`
(`field1`,
`field2`)
SELECT value1,
value2
FROM (SELECT 1) t_1
WHERE NOT EXISTS (SELECT 1
FROM `table1`
WHERE `field1` = value1
AND `field2` = value2);
For yor question it could be written as
INSERT INTO `activity`
(`serialNumbers`,
`active`)
SELECT 1234,
'yes'
FROM (SELECT 1) t_1
WHERE EXISTS (SELECT 1
FROM `activity`
WHERE `serialNumbers` = 1234
AND `active` = 'no');
You can use the ON DUPLICATE KEY statement after an INSERT INTO query to update the row if it already exists. Documentation : https://dev.mysql.com/doc/refman/5.0/en/insert-on-duplicate.html
INSERT INTO table (serialNumber , active, country) VALUES (1010, 'no', 'FR')
ON DUPLICATE KEY UPDATE active='yes';
You can use the insert ... on duplicate key update in MySQL. It is similar to the MERGE used in other SQL databases, but MySQL does not provide the MERGE statement so this is the next best.
INSERT INTO TABLE (serialNumber, active, country)
VALUES (1234, 'active', 'GB') ON DUPLICATE KEY UPDATE country = 'ND';
Also, use INSERT IGNORE if you don't want to generate errors.
