here is my 3 tables:
table 1 — stores user information and it has unique data
table 2 — stores place category such as, toronto, ny, london, etc hence this is is also unique
table 3 — has duplicate information. it stores all the places a user have been.
the 3 tables are linked or joined by these ids:
table 1 has an “table1_id”
table 2 has an “table2_id” and “place_name”
table 3 has an “table3_id”, “table1_id”, “place_name”
i have an interface where an admin sees all users. beside a user is “edit” button. clicking on that edit button allows you to edit a specific user in a form fields which has a multiple drop down box for “places”.
if an admin edits a user and add 1 “places” for the user, i insert that information using php. if the admin decides to deselect that 1 “places” do i delete it or mark it as on and off? how about if the admin decides to select 2 “places” for the user; change the first “places” and add an additional “places”. will my table just keep growing and will i have just redundant information?
thanks.
Tables 1 and 2 sound correct. Table 3 should not contain place_name. Instead, you should have foreign key references to both table1_id and table2_id (you can optionally keep table3_id). This makes table3 a junction table.
When you want to delete a place for a user, you’ll delete a row in table_3 (and that’s it). When adding a place, you first check if it exists in table 1. If not, you add it to table 1. Then, you add a row to table 3. A change (e.g. renaming a place in the UI for a user) should be broken down into a delete then add.
This will avoid redundant information.