Boost C++ Libraries

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metadata_collection_view

A read-only view of a collection of metadata objects.

Synopsis

Defined in header <boost/mysql/metadata_collection_view.hpp>

using metadata_collection_view = boost::span< const metadata >;

Member Functions

Name	Description
column_collation	Returns the ID of the collation that fields belonging to this column use.
column_length	Returns the maximum length of the column.
column_name	Returns the actual name of the column.
database	Returns the name of the database (schema) the column belongs to.
decimals	Returns the number of decimals of the column.
has_no_default_value	Returns `true` if the column does not have a default value.
is_auto_increment	Returns `true` if the column is defined as `AUTO_INCREMENT`.
is_multiple_key	Returns `true` if the column is part of a `KEY` (but not a `UNIQUE KEY` or `PRIMARY KEY`).
is_not_null	Returns `true` if the column is not allowed to be NULL, `false` if it is nullable.
is_primary_key	Returns `true` if the column is part of a `PRIMARY KEY`.
is_set_to_now_on_update	Returns `true` if the column is defined as `ON UPDATE CURRENT_TIMESTAMP`.
is_unique_key	Returns `true` if the column is part of a `UNIQUE KEY` (but not a `PRIMARY KEY`).
is_unsigned	Returns `true` if the column has no sign (is `UNSIGNED`).
is_zerofill	Returns `true` if the column is defined as `ZEROFILL` (padded to its maximum length by zeros).
metadata	Default constructor. — Move constructor. — Copy constructor.
operator=	Move assignment. — Copy assignment.
original_column_name	Returns the original (physical) name of the column.
original_table	Returns the name of the physical table the column belongs to.
table	Returns the name of the virtual table the column belongs to.
type	Returns the type of the column (see `column_type` for more info).
~metadata [destructor]	Destructor.

This is a regular, value type. Instances of this class are not created by the user directly, but by the library.

Object lifetimes

The object doesn't own the storage for the metadata objects. These are typically owned by a results or execution_state object. This view is valid as long as the memory allocated for the metadata objects remain valid.