ReadMediaHeader Method (BackupDevice)
后续版本的 Microsoft SQL Server 将删除该功能。请避免在新的开发工作中使用该功能，并着手修改当前还在使用该功能的应用程序。
The ReadMediaHeader method returns a QueryResults object that enumerates the values of a backup media header record.
语法
object
.ReadMediaHeader(
)
as
QueryResults
Parts
- object
Expression that evaluates to an object in the Applies To list.
Prototype (C/C++)
HRESULT ReadMediaHeader(
LPSQLDMOQUERYRESULTS* ppResults);
Returns
A QueryResults object containing zero or one result set defined by these columns.
Column |
Data type |
Description |
|---|---|---|
MediaName |
nvarchar(130) |
Name of the media. |
MediaSetId |
nvarchar(39) |
System-generated unique identifier for the media set. |
FamilyCount |
integer |
Number of families within the media set. |
FamilySequenceNumber |
integer |
Ordinal position of the family within the entire media set. |
MediaFamilyId |
nvarchar(39) |
System-generated unique identifier for the media family. |
MediaSequenceNumber |
integer |
Ordinal position of the media within its family. |
MediaLabelPresent |
tinyint |
When 1, the MediaDescription column reports the contents of the Microsoft Tape Format label. When 0, no label is present for the media. The MediaDescription column reports informative text. |
MediaDescription |
nvarchar(256) |
Descriptive text. Interpret by using the value returned in the MediaLabelPresent column. |
SoftwareName |
nvarchar(65) |
Name of the product creating the media header. |
SoftwareVendorId |
integer |
Unique identifier of the manufacturer of the product creating the media header. |
MediaDate |
smalldatetime |
Creation date and time of the media header. |
注释
A database backup performed by Microsoft SQL Server can target multiple devices of a single type and can span multiple media maintained by the device. To organize media used in backup, SQL Server defines the media set and media family. A media label, or header record, maintains data about a media's location within a media set and media family.
When the media of a backup device is unused or unlabeled, such as when a disk device is empty, the ReadMediaHeader method succeeds, returning an empty QueryResults object.