In Hibernate, a dialect is a class that acts as a bridge between Java JDBC types and SQL types, which contains the mapping between Java language data type and database datatype. It allows Hibernate to generate SQL optimized for a particular relational database. Hibernate generates queries for the specific database based on the Dialect class. The dialect specifies the type of database used in Hibernate so that Hibernate can switch to the database-specific SQL generator code.
Dialects can be used in the following ways:
- To generate optimized SQL queries
- To interact with a particular database if the application works with the help of more than one database
- To set default values for Hibernate configuration file properties based on the database software even though they are not specified in the configuration file
The SQL dialect converts the HQL query which we write in Java or any other object-oriented program to the specific database SQL query. If a dialect is specified, Hibernate will use sensible defaults for some of the other properties, which means that they do not have to be specified manually.
There are many Dialects classes defined for RDBMS in the org.hibernate.dialect package. Some examples of dialects are:
- MySQL5Dialect: An SQL dialect for MySQL 5.x specific features
- Oracle10gDialect: A dialect specifically for use with Oracle 10g
- SQLServerDialect: An SQL dialect for Microsoft SQL Server 2000
In summary, a dialect in Hibernate is a class that specifies the type of database used in Hibernate so that Hibernate can generate appropriate type of SQL statements. It allows Hibernate to generate SQL optimized for a particular relational database and to interact with a particular database if the application works with the help of more than one database.
