To view the properties of a relational source column or a column in a user-defined table:
In the Data Source Navigator, under Data Sources in the physical tree, expand the appropriate data source connection, and navigate to the relational source column or the column in a user-defined table whose properties you want to view.
Right-click the column and select Properties, and then select the Columns tab.
These column properties are displayed:
Whether a column is a key column
Column name
Column type
Whether nulls are allowed
To view the properties of tables and columns in a minischema, see Viewing Properties of Minischema Tables and Columns.