ArcGIS Learning records The differences between-union, merge, and append

Original address:

ArcGIS Issue: Key differences between union, Merge, and append [goto]-Silent Dawn's blog-NetEase Blogs
http://gisman.blog.163.com/blog/static/3449338820094279425963/

The tools for merging two feature classes into one in Arctoolbox are mainly union, merge, and append. Although all of them can merge two feature classes
into a feature class, but functionally different, the main differences between them are described below.
The following two graphs are the graphs and attribute tables for two feature classes A, B:

1. Union: Merge the input feature classes into the new feature class.
Graphics: Union can only merge feature classes of type polygon. When two feature classes are merged, the intersecting parts are processed to form multipart features individually, with options to allow gaps (gaps) or gaps to be allowed. If you choose not to allow a gap, the merged gap of the two feature classes will generate features.
Property sheet: There are three options for the Union Merge property sheet: All, No_fid, and Only_fid. All the attribute table fields of the two feature classes are placed in the order of the attribute tables of the output feature class, including the FID. Fields with the same name (except FID) are followed by a number in the field name (FID and feature class name). No_fid fields in the attribute table of the two feature classes are placed in the order of the attribute tables of the output feature class, except for the FID. Only_fid only the FID from the attribute table of the two feature classes into the attribute table of the output feature class, adding the feature class name to differentiate after the FID. Union does not do field mapping.

2, Merge: Merge Input feature class, table into new feature class, table.
Graphics: Merge can merge feature classes and tables, such as points, lines, and polygons, but must be of the same type. Merge does not process features, it simply places features in a feature class, so the output feature classes may have overlapping or gaps.
Property sheet: When the merge process attribute table, the fields of the same name are synthesized one, and the fields of different names are added to the Output feature class attribute table in the original name and order, and the original FID is discarded. The merge can be field mapped.

3. Append: Merges input feature classes, tables, raster images, and raster catalogs into an existing feature class, table, raster image, and raster catalog. When the schema type option is test, the feature class attribute table structure for the input and output must be identical, with the field name, type, and order must be exactly the same, which can be different when the schema type option is No_test.
Graphics: Append can combine feature classes and tables, raster imagery, and raster catalogs, such as points, lines, and polygons, but must be of the same type. Append does not process features, it simply places features in a feature class, so the output feature classes may have overlapping or gaps.
Property sheet: The attribute table of the same output feature class. fields in the Input feature class attribute table will be discarded if not in the Output feature class attribute table, but you can do field mapping to map a field of the input feature class to a field in the Output feature class.

ArcGIS Learning records The differences between-union, merge, and append