# Editor example Join tables - link table

Data in relational databases is often stored over multiple tables, partitioned by the data type and then joined together using SQL JOIN queries. In one form of joined table, a 'link' table is used linking records between two different types of data.

In this example, which extends the simple join example, the `users` and `dept` tables are linked by the `user_dept` table. When the data is read, we read from all three tables (plus the `sites` table to show multiple joins working together). The returned data structure for each row in this example is:

    {
    	"DT_RowId": "row_1",
    	"users": {
    		"first_name": "Quynn",
    		"last_name": "Contreras",
    		"site": "1"
    	},
    	"sites": {
    		"name": "Edinburgh"
    	},
    	"user_dept": {
    		"dept_id": "1"
    	},
    	"dept": {
    		"name": "IT"
    	}
    }

For editing we want to write to three `users` fields and the `user_dept` field. The Editor instance is configured with these four fields using the `fields.name` option and the Editor server-side libraries perform the required SQL operations for us on create, edit and delete.

See the join documentation (PHP | .NET | NodeJS) for further information about joins with Editor's framework libraries.

First name | Last name | Location | Department
--- | --- | --- | ---
First name | Last name | Location | Department

- Javascript
- HTML
- CSS
- Ajax
- Server-side script

The Javascript shown below is used to initialise the table shown in this example:

`var editor; // use a global for the submit and return data rendering in the examples $(document).ready(function() { editor = new $.fn.dataTable.Editor( { ajax: "../../controllers/joinLinkTable.php", table: "#example", fields: [ { label: "First name:", name: "users.first_name" }, { label: "Last name:", name: "users.last_name" }, { label: "Site:", name: "users.site", type: "select" }, { label: "Department:", name: "user_dept.dept_id", type: "select" } ] } ); $('#example').DataTable( { dom: "Bfrtip", ajax: { url: "../../controllers/joinLinkTable.php", type: 'POST' }, columns: [ { data: "users.first_name" }, { data: "users.last_name" }, { data: "sites.name" }, { data: "dept.name" } ], select: true, buttons: [ { extend: "create", editor: editor }, { extend: "edit", editor: editor }, { extend: "remove", editor: editor } ] } ); } );`

In addition to the above code, the following Javascript library files are loaded for use in this example:

- https://code.jquery.com/jquery-3.3.1.js
- https://cdn.datatables.net/1.10.20/js/jquery.dataTables.min.js
- https://cdn.datatables.net/buttons/1.6.0/js/dataTables.buttons.min.js
- https://cdn.datatables.net/select/1.3.1/js/dataTables.select.min.js
- ../../js/dataTables.editor.min.js

The HTML shown below is the raw HTML table element, before it has been enhanced by DataTables:

This example uses a little bit of additional CSS beyond what is loaded from the library files (below), in order to correctly display the table. The additional CSS used is shown below:

``

The following CSS library files are loaded for use in this example to provide the styling of the table:

- https://cdn.datatables.net/1.10.20/css/jquery.dataTables.min.css
- https://cdn.datatables.net/buttons/1.6.0/css/buttons.dataTables.min.css
- https://cdn.datatables.net/select/1.3.1/css/select.dataTables.min.css
- ../../css/editor.dataTables.min.css

This table loads data by Ajax. The latest data that has been loaded is shown below. This data will update automatically as any additional data is loaded.

The script used to perform the server-side processing for this table is shown below. Please note that this is just an example script using PHP. Server-side processing scripts can be written in any language, using the protocol described in the DataTables documentation.