Simplifying Update/Insert conditionals SQL - mysql

Question

I have the following stored procedure that takes a key and a timestamp and updates the timestamp using the key if the key is already present, otherwise it inserts the key along with the accompanying timestamp value:
CREATE PROCEDURE `sp_AddUpdateTimestamp`(IN timestampKey VARCHAR(50), IN timestampValue TIMESTAMP)
BEGIN
IF(timestampKey IS NOT NULL) THEN
IF(timestampValue IS NOT NULL) THEN
IF EXISTS (SELECT Name FROM StoredTimestamps WHERE Name = timestampKey) THEN
UPDATE StoredTimestamps SET Timestamp = timestampValue WHERE Name = timestampKey;
ELSE
INSERT INTO StoredTimestamps (Name, Timestamp) VALUES (timestampKey, timestampValue);
END IF;
ELSE
IF EXISTS (SELECT Name FROM StoredTimestamps WHERE Name = timestampKey) THEN
UPDATE StoredTimestamps SET Timestamp = NOW() WHERE Name = timestampKey;
ELSE
INSERT INTO StoredTimestamps (Name, Timestamp) VALUES (timestampKey, NOW());
END IF;
END IF;
END IF;
END
To me, this is a lot of conditional logic and makes this procedure very verbose. Does anyone know a way this logic can be simplified?

Answer 1

You want INSERT ON DUPLICATE KEY UPDATE:
INSERT INTO StoredTimestamps (Name, Timestamp)
VALUES (timestampKey, COALESCE(timestampValue, NOW()) )
ON DUPLICATE KEY UPDATE Timestamp = VALUES(timestampValue);
The ON DUPLICATE KEY sets the Timestamp to the value being inserted, when the Name already exists.
For this to work, you need a unique index/constraint on Name:
ALTER TABLE StoredTimestamps ADD CONSTRAINT unq_StoredTimestamps_Name UNIQUE (Name);
In a stored procedure, I would be careful about naming conventions as well:
CREATE PROCEDURE usp_AddUpdateTimestamp (
IN in_timestampKey VARCHAR(50),
IN in_timestampValue TIMESTAMP)
)
BEGIN
INSERT INTO StoredTimestamps (Name, Timestamp)
VALUES (in_timestampKey, COALESCE(in_timestampValue, NOW()))
ON DUPLICATE KEY UPDATE Timestamp = VALUES(timestampValue)
END;
I prefer usp_ rather than sp_ due to my history of using SQL Server, where sp_ is discouraged because it is used for system stored procedures. That is simply a habit and not really relevant to MySQL.