DB2 Add Column to DB2 Database Tables via the Alter Table Command. DB2 Change Column Type of DB2 Database Table Columns via the Alter Table Command. H2 Database Engine. Features. Feature List Comparison to Other Database Engines H2 in Use Connection Modes Database URL Overview Connecting to an Embedded (Local) Database In-Memory Databases Database Files Encryption Database File Locking Opening a Database Only if it Already Exists Closing a Database Ignore Unknown Settings Changing Other Settings when Opening a Connection Custom File Access Mode Multiple Connections Database File Layout Logging and Recovery Compatibility Auto-Reconnect Automatic Mixed Mode Page Size Using the Trace Options Using Other Logging APIs Read Only Databases Read Only Databases in Zip or Jar File Computed Columns / Function Based Index Multi-Dimensional Indexes User-Defined Functions and Stored Procedures Pluggable or User-Defined Tables Triggers Compacting a Database Cache Settings Feature List Main Features.