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The purpose of the where clause is for you to specify which record you want.

Looks like you might have confused WHERE with LIMIT.

Example data TABLE: client TABLE: project +----+-----------+----------+ +----+---------------+-----------+------------+ | id | firstname | lastname | | id | project_name | client_id | start_date | +----+-----------+----------+ +----+---------------+-----------+------------+ | 1 | Scott | Chegg | | 1 | Project Alpha | 4 | 2022-12-01 | | 2 | Laura | Norder | | 2 | Proect Beta | 2 | 2023-01-15 | | 3 | Tom | DiCanari | | 3 | Project Gamma | 4 | 2023-03-01 | | 4 | S | Tonin | | 4 | Project Delta | 1 | 2023-03-20 | +----+-----------+----------+ +----+---------------+-----------+------------+ Query SELECT project_name , start_date , CONCAT(c.firstname, ' ', c.lastname) as client FROM project p JOIN client c ON p.client_id = c.id ORDER BY client, start_date; +---------------+------------+--------------+ | project_name | start_date | client | +---------------+------------+--------------+ | Proect Beta | 2023-01-15 | Laura Norder | | Project Alpha | 2022-12-01 | S Tonin | | Project Gamma | 2023-03-01 | S Tonin | | Project Delta | 2023-03-20 | Scott Chegg | +---------------+------------+--------------+ Now change the first name of client 4 and re-query UPDATE client SET firstname = 'Sarah' WHERE id = 4; SELECT project_name , start_date , CONCAT(c.firstname, ' ', c.lastname) as client FROM project p JOIN client c ON p.client_id = c.id ORDER BY client, start_date; +---------------+------------+--------------+ | project_name | start_date | client | +---------------+------------+--------------+ | Proect Beta | 2023-01-15 | Laura Norder | | Project Alpha | 2022-12-01 | Sarah Tonin | | Project Gamma | 2023-03-01 | Sarah Tonin | | Project Delta | 2023-03-20 | Scott Chegg | +---------------+------------+--------------+

It is not possible to know the MAC address of a client's computer. At all. You'll need to find an alternative method to identify a user.