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85 lines
3.3 KiB
85 lines
3.3 KiB
2 years ago
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.. _relations:
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Relations
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=========
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phpMyAdmin allows relationships (similar to foreign keys) using MySQL-native
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(InnoDB) methods when available and falling back on special phpMyAdmin-only
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features when needed. There are two ways of editing these relations, with the
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*relation view* and the drag-and-drop *designer* -- both of which are explained
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on this page.
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.. note::
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You need to have configured the :ref:`linked-tables` for using phpMyAdmin
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only relations.
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Technical info
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--------------
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Currently the only MySQL table type that natively supports relationships is
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InnoDB. When using an InnoDB table, phpMyAdmin will create real InnoDB
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relations which will be enforced by MySQL no matter which application accesses
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the database. In the case of any other table type, phpMyAdmin enforces the
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relations internally and those relations are not applied to any other
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application.
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Relation view
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-------------
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In order to get it working, you first have to properly create the
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[[pmadb|pmadb]]. Once that is setup, select a table's "Structure" page. Below
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the table definition, a link called "Relation view" is shown. If you click that
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link, a page will be shown that offers you to create a link to another table
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for any (most) fields. Only PRIMARY KEYS are shown there, so if the field you
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are referring to is not shown, you most likely are doing something wrong. The
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drop-down at the bottom is the field which will be used as the name for a
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record.
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Relation view example
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+++++++++++++++++++++
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.. image:: images/pma-relations-relation-view-link.png
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.. image:: images/pma-relations-relation-link.png
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Let's say you have categories and links and one category can contain several links. Your table structure would be something like this:
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- `category.category_id` (must be unique)
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- `category.name`
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- `link.link_id`
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- `link.category_id`
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- `link.uri`.
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Open the relation view (below the table structure) page for the `link` table and for `category_id` field, you select `category.category_id` as master record.
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If you now browse the link table, the `category_id` field will be a clickable hyperlink to the proper category record. But all you see is just the `category_id`, not the name of the category.
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.. image:: images/pma-relations-relation-name.png
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To fix this, open the relation view of the `category` table and in the drop down at the bottom, select "name". If you now browse the link table again and hover the mouse over the `category_id` hyperlink, the value from the related category will be shown as tooltip.
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.. image:: images/pma-relations-links.png
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Designer
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--------
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The Designer feature is a graphical way of creating, editing, and displaying
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phpMyAdmin relations. These relations are compatible with those created in
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phpMyAdmin's relation view.
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To use this feature, you need a properly configured :ref:`linked-tables` and
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must have the :config:option:`$cfg['Servers'][$i]['table_coords']` configured.
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To use the designer, select a database's structure page, then look for the
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:guilabel:`Designer` tab.
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To export the view into PDF, you have to create PDF pages first. The Designer
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creates the layout, how the tables shall be displayed. To finally export the
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view, you have to create this with a PDF page and select your layout, which you
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have created with the designer.
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.. seealso::
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:ref:`faqpdf`
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