名稱
ST_BandMetaData — 傳回特定光柵波段的基本中繼資料。若未指定波段編號，則預設為波段 1。
概要
(1) record ST_BandMetaData(raster rast, integer band=1);
(2) record ST_BandMetaData(raster rast, integer[] band);
描述
傳回關於光柵波段的基本中繼資料。傳回的欄位包括：pixeltype、nodatavalue、isoutdb、path、outdbbandnum、filesize、filetimestamp。
![[Note]](../images/note.png)
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如果光柵不包含任何波段，則會拋出錯誤。 |
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如果波段沒有 NODATA 值，則 nodatavalue 為 NULL。 |
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如果 isoutdb 為 False，則 path、outdbbandnum、filesize 和 filetimestamp 為 NULL。如果停用 outdb 存取，則 filesize 和 filetimestamp 也將為 NULL。 |
增強功能：2.5.0 版新增了針對 outdb 光柵的 outdbbandnum、filesize 和 filetimestamp。
範例：變體 1
SELECT
rid,
(foo.md).*
FROM (
SELECT
rid,
ST_BandMetaData(rast, 1) AS md
FROM dummy_rast
WHERE rid=2
) As foo;
rid | pixeltype | nodatavalue | isoutdb | path | outdbbandnum
-----+-----------+---- --------+---------+------+--------------
2 | 8BUI | 0 | f | |
範例：變體 2
WITH foo AS (
SELECT
ST_AddBand(NULL::raster, '/home/pele/devel/geo/postgis-git/raster/test/regress/loader/Projected.tif', NULL::int[]) AS rast
)
SELECT
*
FROM ST_BandMetadata(
(SELECT rast FROM foo),
ARRAY[1,3,2]::int[]
);
bandnum | pixeltype | nodatavalue | isoutdb | path | outdbbandnum | filesize | filetimestamp |
---------+-----------+-------------+---------+--------------------------------------------------------------------------------+---------------+----------+---------------+-
1 | 8BUI | | t | /home/pele/devel/geo/postgis-git/raster/test/regress/loader/Projected.tif | 1 | 12345 | 1521807257 |
3 | 8BUI | | t | /home/pele/devel/geo/postgis-git/raster/test/regress/loader/Projected.tif | 3 | 12345 | 1521807257 |
2 | 8BUI | | t | /home/pele/devel/geo/postgis-git/raster/test/regress/loader/Projected.tif | 2 | 12345 | 1521807257 |