Question

I’m working with a pseudo sessions table in MySQL. The table looks like this currently:

id   |   key   |   value   |   metadata

The id is the user that the session belongs to and metadata is the IP Address of the user. The idea behind this is that each user can be logged in multiple times from different IP Addresses. I’m wondering if REPLACE INTO can Replace values only where id = userid, key = key, AND metadata = ip_address so ideally we can end up with something like this:

id   |   key   |   value   |   metadata
 1       test      avalue       127001
 1       test      bvalue       19216801
 1       test      cvalue       19215810

Is something like that possible?

Answer 1

If you have a UNIQUE index or PRIMARY KEY defined across those three columns, then yes you can REPLACE INTO it. Add the index if you do not already have it:

ALTER TABLE session_table ADD PRIMARY KEY (`id`, `key`, `metadata`); 

If you already have a PK defined, create a composite UNIQUE index across those columns:

CREATE INDEX `idx_id_key_metadata` ON session_table (`id`, `key`, `metadata`); 

More on the MySQL CREATE INDEX syntax

Here’s a little demonstration.