Should i place Registered-Users Info in every table? to Restrict user access to his Own Data only
For table-level access restrictions:

GRANT SELECT ON tbl1 TO 'user'@'...';
GRANT SELECT ON tbl3 TO 'user'@'...';


Repeat as needed for each combination of user and table.

If you have a newer version of MySQL, see if "Roles" provides a simplification.

For row-level access restrictions, do not let the users query the tables.  Instead:


Provide an app that they contact; it checks permissions before preforming (or not) the desired query.
Use Stored Procedures.  See also the function CURRENT_USER()
Use a VIEW -- then grant access to the view but not the table; have the view check whether the user is allowed to see the row.  See OP's comment.