Linking tables in Manifold
Table linking is the option of GIS tools to be able to associate data from different sources but that share a common field. This is what we did in ArcView as a "join", Manifold allows us to do it both dynamically, that is, the data is only associated; as well as in an unlinked way, which makes the data come as a copy to the table in use.
What kind of tables
Manifold allows you to handle different table shapes, including:
- Ordinary tables. These are those created from within Manifold, with the option "file / create / table"
- Imported Tables. These are the ones that have been fully entered, such as the tables supported by Access components (CSV, DBF, MDB, XLS, etc.) or through ADO .NET, ODBC or OLE DB data source connectors.
- Linked Tables. These are similar to the imported ones, but they are not entered inside the .map file, but it can be an excel file that is external and is only "linked", they can be Access components (CSV, DBF, MDB, XLS, etc. ) or through ADO .NET, ODBC or OLE DB data source connectors.
- Tables linked to a drawing. They are those that belong to a map, such as the dbf of a shapefile, or tables of attributes of vector files (dgn, dwg, dxf…)
- Queries. These are tables created from internal queries between tables.
How to do it
- The table that will show the additional fields is opened and the "Table / Relations" option is accessed.
- We choose the “New Relation” option.
- In the Add Relation dialog, choose another table from the list shown. Here you choose if you want to import or link the data.
- Then a field is selected in each table that will be used to synchronize the data and OK is pressed.
Back to the "Add Relation" dialog, the desired columns of the other table are checked with a check. Then press OK.
The result
Columns that are “borrowed” from the other table will appear with a different background color to indicate that they are “linked”. You can perform operations on it like any other column, for example sort, filter, in formulas, or in theming. Tables can have more than one relationship with more than one table.
