What is Dialect?

The Dialect describes the SQL behaviour of the JDBC driver and database to which the application is connecting.
In hibernate.cfg.xml configuration file, the hibernate.dialect property should be set to the correct org.hibernate.dialect.Dialect subclass for the application database. If a dialect is specified, Hibernate will use sensible defaults for some of the other properties. This means that they do not have to be specified manually.
The org.hibernate.dialect package abstracts the SQL dialect of the underlying database.
Cache71DialectCaché 2007.1 dialect. org.hibernate.dialect.Cache71Dialect
This class is required in order to use Hibernate with Intersystems Cache SQL.
DB2390DialectAn SQL dialect for DB2/390. org.hibernate.dialect.DB2390Dialect
DB2400DialectAn SQL dialect for DB2/400.
 DB2Dialect An SQL dialect for DB2.
 DerbyDialect Hibernate Dialect for Cloudscape 10 – aka Derby. org.hibernate.dialect.DerbyDialect
DerbyTenFiveDialectDialect for Derby 10.5org.hibernate.dialect.DerbyTenFiveDialect
DerbyTenSixDialect Dialect for Derby 10.6org.hibernate.dialect.DerbyTenSixDialect
DerbyTenSevenDialect Dialect for Derby 10.7org.hibernate.dialect.DerbyTenSevenDialect
About Firebird
 An SQL dialect for Firebird.
 FrontBaseDialect An SQL Dialect for Frontbase.
 H2Dialect A dialect compatible with the H2 database.
About Hana
An SQL dialect for HANA Column Store.org.hibernate.dialect.HANAColumnStoreDialect
HANARowStoreDialectAn SQL dialect for HANA Row Store.org.hibernate.dialect.HANARowStoreDialect
 HSQLDialect An SQL dialect compatible with HSQLDB (HyperSQL).
 InformixDialect Informix dialect. org.hibernate.dialect.InformixDialect
 Ingres10Dialect A SQL dialect for Ingres 10 and later versions.
 Ingres9Dialect A SQL dialect for Ingres 9.3 and later versions.
 IngresDialect An SQL dialect for Ingres 9.2. org.hibernate.dialect.IngresDialect
 InterbaseDialect An SQL dialect for Interbase. org.hibernate.dialect.InterbaseDialect
 JDataStoreDialect A Dialect for JDataStore. org.hibernate.dialect.JDataStoreDialect
 MckoiDialect An SQL dialect compatible with McKoi SQL org.hibernate.dialect.MckoiDialect
 MimerSQLDialect An Hibernate 3 SQL dialect for Mimer SQL. org.hibernate.dialect.MimerSQLDialect
 MySQL5Dialect An SQL dialect for MySQL 5.x specific features.
 MySQLDialect An SQL dialect for MySQL (prior to 5.x).
 Oracle10gDialect A dialect specifically for use with Oracle 10g.
 Oracle8iDialect A dialect for Oracle 8i.
 Oracle9Dialect Deprecated. Use either Oracle9iDialect or Oracle10gDialect instead
 Oracle9iDialect A dialect for Oracle 9i databases.
 OracleDialect Deprecated. Use Oracle8iDialect instead.
 PointbaseDialect A Dialect for Pointbase. org.hibernate.dialect.PointbaseDialect
PostgreSQL81DialectAn SQL dialect for Postgres 8.1org.hibernate.dialect.PostgreSQL81Dialect
PostgreSQL82DialectAn SQL dialect for Postgres 8.2org.hibernate.dialect.PostgreSQL82Dialect
PostgreSQL9DialectAn SQL dialect for Postgres 9org.hibernate.dialect.PostgreSQL9Dialect
 PostgresPlusDialect An SQL dialect for Postgres Plus
 PostgreSQLDialect An SQL dialect for Postgres
 ProgressDialect An SQL dialect compatible with Progress 9.1C
 RDMSOS2200Dialect This is the Hibernate dialect for the Unisys 2200 Relational Database (RDMS). org.hibernate.dialect.RDMSOS2200Dialect
 SAPDBDialect An SQL dialect compatible with SAP DB. org.hibernate.dialect.SAPDBDialect
 SQLServer2008Dialect A dialect for Microsoft SQL Server 2008 with JDBC Driver 3.0 and above
 SQLServerDialect A dialect for Microsoft SQL Server 2000 and 2005 org.hibernate.dialect.SQLServerDialect
 Sybase11Dialect A SQL dialect suitable for use with Sybase 11.9.2 (specifically: avoids ANSI JOIN syntax)
 SybaseAnywhereDialect SQL Dialect for Sybase Anywhere extending Sybase (Enterprise) Dialect (Tested on ASA 8.x)
 SybaseASE15Dialect An SQL dialect targetting Sybase Adaptive Server Enterprise (ASE) 15 and higher.
 SybaseDialect Deprecated. use AbstractTransactSQLDialect, SybaseASE15Dialect or SQLServerDialect instead depending on need.
 TeradataDialect A dialect for the Teradata database created by MCR as part of the dialect certification process.
 TimesTenDialect A SQL dialect for TimesTen 5.1. It is a Oracle database.org.hibernate.dialect.TimesTenDialect