Adding data to an existing table and editing that data in the table are important parts of maintaining a current and complete GIS. There are several ways to add data to tables.
You can add data to an existing table by pasting values from other applications such as Microsoft Excel . Copy and paste is a recommended workflow to update and replace existing values with new information. If more rows are pasted than currently exist in the database table's row count, additional rows are automatically created.
If more columns are pasted than currently exist, additional columns are dropped.
You can add data to an existing table by pasting values copied from another table in either the same or a different ArcGIS Pro project. Copy and paste is a recommended workflow to update and replace existing values with new information. If more rows are pasted than currently exist in the database table's row count, additional rows are automatically created. However, if more columns are pasted than currently exist, additional columns are dropped.
With geoprocessing, you can use tools to update existing fields, append records to a table permanently, or append fields to a table dynamically with a join.
You can use the Calculate Field tool to update existing fields or newly created fields for a feature class, feature layer, or raster catalog. You can calculate numbers, text, or date values into a field. Using code blocks, you can write scripts to perform advanced calculations.
The Add Join tool links the fields from the join table to a base table.
Typically, you'll join a table of data to a layer based on the value of a field that exists in both tables. The names of the fields do not need to be the same, but the data type does; you join numbers to numbers, strings to strings, and so on.
When you create a joined table, you can use the appended fields in field calculations or for labeling, symbolizing, or querying the data. The fields that are appended from the join table are not permanently attached to the base table. You can undo joins to remove the appended fields.
The Join Field tool appends the contents from one table to another table based on a common field. You can optionally define which fields from the join table will be added to the input table.
When using this workflow, the fields are permanently added to your base table.
The Add Field tool adds a field to your current table or the table of a feature class, feature layer, raster catalog, or raster with an attribute table. Use Calculate Field to populate newly added fields.
Use the Append tool to add features or other data from multiple datasets to an existing dataset. This tool can append point, line, or polygon feature classes; tables; rasters; raster catalogs; annotation feature classes; or dimensions feature classes to an existing dataset of the same type. For example, you can append several tables to an existing table or several rasters to an existing raster dataset, but you cannot append a line feature class to a point feature class.
The Calculate Geometry Attributes tool adds information to a feature's attribute fields representing the spatial or geometric characteristics and location of each feature, such as length or area and x-, y-, z-, and m-coordinates.
Feature class attribute tables support the addition of stand-alone rows. To do so, click the Click to add new row option from within the attribute table.
Control the appearance of this option on the Table tab of the project options.
You can insert rows into an active stand-alone table. Click the Insert Rows button and provide the Number of rows value to add to the table. Click Create or press Enter . The new rows are added to the bottom of the table, selected, and the first newly added row has focus.
You can create a duplicate copy of the attributes of a feature or record. Right-click the row header and click Duplicate Row to create a copy of the chosen row at the bottom of the table. It is selected. The geometry of a feature is included when duplicating a row.
The Fields view is used to manage the fields associated with a table. In the Fields view, you can edit a table's fields and modify field properties, delete fields, or create fields. To open the Fields view, right-click a column heading in the table and click Fields 
. You can also click Add Field 
from the table view's built-in toolbar to open the Fields view to add a field.
