The <= operator compares two raster objects by their universally unique identifiers (UUIDs) and returns true if the UUID of the first object is less than or equal to the UUID of the second.
Note This operator compares UUIDs only — it does not compare spatial extents or pixel types. Use it only for operations that require ordering or indexing raster objects, such as union and B-tree operations.
Syntax
bool Operator <=(raster rast1, raster rast2)Parameters
| Parameter | Description |
rast1 | The first raster object. |
rast2 | The second raster object. |
Example
The following query uses <= to compare the UUID of each raster in tbl_a against the UUID of the corresponding raster in tbl_b:
SELECT a.rast <= b.rast
FROM tbl_a a, tbl_b b
WHERE a.id = b.id该文章对您有帮助吗？