HSQLDB – Java database

Hyper Structured Query Language Database (HSQLDB) is an SQL relational database management system written in Java. It has a JDBC driver conforming to ANSI SQL:2008 and supports a rich subset of SQL-92 (BNF tree format) plus SQL:1999 and SQL:2003 enhancements. It is a small, fast, multithreaded engine and server with in-memory and disk based tables, LOBs, transaction isolation, encryption and ACID.

HSQLDB offers a small, fast database engine that offers both in-memory and disk-based tables.

There are embedded and server modes available. Additionally, this package includes tools such as a minimal web server, in-memory query and management tools (can be run as applets), and a number of demonstration examples.

HSQLDB is used as a database and persistence engine in many open source software projects, such as OpenOffice.org, Kurlo, JBoss, Spring Framework as well as in commercial products, such as Mathematica and Hedgehog.

Features include:


  • 100% Java.
  • Support JDK 1.1.x, 1.2.x, 1.3.x, 1.4.x.
  • Extensive JDBC interface support with batch statement and scrollable ResultSet functionality.
  • Updatable, insertable ResultSet functionality.
  • Full JDBC DatabaseMetaData and ResultSetMetaData support.
  • Java stored procedures and functions.
  • Full support for PreparedStatement objects to speed up query processing.


  • Relational Database Management System, which can store Serializable Java objects.
  • Very extensive support for SQL:2008 Standard syntax, including most optional features.
  • Supports all base data types of the SQL Standard, including BINARY, BIT, BOOLEAN, date-time, INTERVAL, BLOB, CLOB.
  • Supports user-defined DOMAIN types, including type constraints.
  • Fast SELECT, INSERT, DELETE, UPDATE and MERGE operations.
  • NATURAL, USING and UNION joins.
  • UNION, EXCEPT, INTERSECT, including use of parentheses, limits and offsets, ALL, DISTINCT and CORRESPONDING keywords.
  • Scalar (single value) SELECTS, row and correlated subqueries including IN, EXISTS, ANY, ALL
  • Views, Temp tables and sequences.
  • Updatable views.
  • Primary key, unique and check constraints on single or multiple columns.
  • Referential Integrity (foreign keys) on multiple columns with full cascading options (delete, update, set null, set default).
  • COUNT, SUM, MIN, MAX, AVG and statistical aggregate functions.
  • Full support for SQL expressions such as CASE .. WHEN .. ELSE .. , NULLIF etc.
  • SQL standard autoincrement column support plus sequences.
  • Transaction COMMIT, ROLLBACK and SAVEPOINT support.
  • Multiple schemata per database.
  • Triggers, implemented as Java classes, or as SQL statements.
  • Database security with passwords, user rights and roles with GRANT and REVOKE.
  • Extensive set of ALTER TABLE commands, including change of table column type.
  • SQL stored procedures and functions.


  • In-memory tables for fastest operation.
  • Disk based tables for large data sets.
  • Text tables with external file data sources such as CSV files.
  • Disk tables (CACHED TABLE) up to 16GB and text tables up to 2GB each.
  • CLOB and BLOB storage up to 16 TB.
  • Size of each string or binary item only limited by memory.
  • Database dump as SQL script with or without data.


  • Embedded (into Java applications) and Client-Server operating modes.
  • Three client server protocols: HSQL, HTTP and HSQL-BER – can run as an HTTP web server – all with SSL option.
  • Can be used in applets, read-only media (CD), inside jars, webstart and embedded applications.
  • Multiple databases per JVM.
  • ODBC support.


  • Powerful and compact java command line and GUI tools for database management.
  • Transfer tool for conversion of databases to / from other popular database management systems.

Website: hsqldb.org
Support: FAQ
Developer: The hsql Development Group
License: BSD License

HSQLDB is written in Java. Learn Java with our recommended free books and free tutorials.

Return to Relational Databases

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