If we have defined an internal relation for the
author table, a new choice appears for the book table: Check referential integrity:
A link (here, author_id -> author.id) appears for each defined relation, and clicking
it starts a verification. For each row, the presence of the corresponding key in the
foreign table is verified, and any errors are reported. If the resulting page reports
zero rows, this is good news!
This operation exists, because for non-InnoDB tables, MySQL does not enforce
referential integrity, and neither does phpMyAdmin. It is perfectly possible, for
example, to import data in the book table with invalid values for author_id.
Automatic Updates of Metadata
phpMyAdmin keeps the metadata for internal relations synchronized with every
change that is made to the tables via phpMyAdmin. For example, renaming a column
that is part of a relation would make phpMyAdmin rename it also in the metadata
for the relation. The same thing happens when a column or a table is dropped.
Metadata should be manually maintained in case a change in the
structure is done from outside phpMyAdmin.
The Relational System
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Column-Commenting
Before MySQL 4.1, the MySQL structure itself does not support adding comments to a
column. Thanks to phpMyAdmin's metadata, we can nevertheless comment columns.
Since MySQL 4.
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