A data quality database refactoring is a change which improves and/or ensures the consistency and usage of the values stored within the database so as to improve your database design without changing its semantics.

Refactoring	Example
Add Lookup Table. Create a lookup table for an existing column.
Apply Standard Codes. Apply a standard set of code values to a single column to ensure that it conforms to the values of similar columns stored elsewhere in the database.
Apply Standard Type. Ensure that the data type of a column is consistent with the data type of other similar columns within the database.
Consolidate Key Strategy. Choose a single key strategy for an entity and apply it consistently throughout your database.
Drop Column Constraint. Remove a column constraint from an existing table.
Drop Default Value. Remove the default value that is provided by a database from an existing table column.
Drop Non-Nullable Constraint. Change an existing non nullable column such that it accepts null values.
Introduce Column Constraint. Introduce a column constraint in an existing table.
Introduce Common Format. Apply a consistent format to all the data values in an existing table column.
Introduce Default Value. Let the database provide a default value for an existing table column.
Make Column Non-Nullable. Change an existing column such that it does not accept any null values.
Move Data. Move the data contained within a table, either all or a subset of its columns, to another existing table.
Replace Type Code With Property Flags. Replace a code column with individual property flags, usually implemented as Boolean columns, within the same table column.