These tools enable the end use to compare the schema and data of two databases, report the differences and script the changes required to synchronise one database with another.
Solution Center - Code examples using Database Comparison Tools
 How can I synchronise two database schemas from within an application

Java Database Comparison Tools by Red-Gate Software

SQL Compare V7.1

SQL Compare compares and synchronizes the structure of Microsoft SQL Server database objects including, but not limited to, tables, stored procedures, views and user-defined functions.

SQL Data Compare V7.1

SQL Data Compare compares and synchronizes the data within Microsoft SQL Server databases. Use SQL Data Compare on its own or as a complement to SQL Compare.

Java Database Comparison Tools by Datanamic Solutions BV

DeZign for Databases 5.0

DeZign for Databases is an intuitive database design tool for developers and DBA's that can help you model, create and maintain databases. It uses entity relationship diagrams to graphically design databases and automatically generates the most popular SQL and desktop databases (Oracle, MySQL, InterBase, PostgreSQL, MS SQL, ..) . You can reverse engineer existing databases, create new databases and modify or compare existing database structures.

Java Database Comparison Tools by Upscene Productions

Database Workbench Pro 3.1.0

Database Workbench Pro is a multi-DBMS developer tool that includes many feature like Diagramming Tools, Test Data Generator, Two-Way Visual Query Builder, Stored Code Debugger, SQL Insight, Parameter Insight, Cross DBMS Migration Tool, Cross DBMS Compare Tool, Visual Object Editors, Metadata Printing and much more.

Java Database Comparison Tools by TulaSoft, LLC

SQL Examiner 2008 V2.0.0.70

SQL Examiner is a database software utility that enables you to compare and synchronize SQL Server database schemas. Now, merging two databases is quick and easy, requiring only a few clicks of your mouse! SQL Examiner delivers precise results by analyzing the dependencies between objects, and your data, and offers step-by-step processing or automatic synchronization. SQL Examiner is compatible with both SQL2000 and SQL2005 Server versions.

Java Database Comparison Tools by The Australian Software Company

SQL Delta 4.1

SQL Delta is a great value, fast SQL database compare tool used to analyze, compare and synchronize database structures and data. SQL Delta compares all database objects including tables, views, stored procedures as well as permissions, user defined functions and so on. SQL Delta will script the differences between two databases.