Here you can find set of easy to use diff & merge utilities for a number of popular database management systems:
These utilities allows to compare and merge both data and database programming objects. They have native two-panel UI commonly used for the most of text diff tools. Here are the most common tools used in all these utilities, by the example of MssqlMerge:
Each utility has Free and Pro versions. Free versions have basic features covering most of primary DB diff & merge tasks: compare table definitions, table data, primary DB programming objects. Data diff can have some limitations based on table definition complexity. Pro versions have no these limitations, they has more convenient UI to observe changes, support more object types and have a number of tools not available in Free version at all.
You may be wondered of the a bit promiscuous list of supported database management systems. Explanation is simple - it is based on author's own experience. He has started with AccdbMerge in 2012, then in 2014 it was adapted to work with Microsoft SQL Server and in 2018 for MySQL and SQLite. Hopefully, in the future more database engines will be supported.