Hibernate - SQL Dialects

Hibernate Dialect is a class that acts as a bridge between Java data types and database-specific SQL types. It helps Hibernate generate SQL queries optimized for a particular database like MySQL, Oracle, etc. Since different databases have different SQL syntax, Dialect ensures compatibility and proper query conversion.

• Enables Hibernate to generate SQL based on the selected database.
• Produces efficient queries tailored to the database features.
• Allows switching between different databases easily.

SQL Dialects Configuration

The SQL dialect converts the HQL query which we write in java or any other object-oriented program to the specific database SQL query. It must be configured in hibernate.cfg.xml to connect Hibernate with a particular database.

<hibernate-configuration>
<session-factory name="session-factory">
<property name="hibernate.dialect">org.hibernate.dialect.DB2Dialect</property>
</session-factory>
</hibernate-configuration>

We can also specify in the properties file as :

hibernate.dialect=org.hibernate.dialect.DB2Dialect

hibernate.dialect property makes Hibernate generate the appropriate SQL statements for the given specific database.

Hibernate Configuration: MySQL dialect

Configuration config = new Configuration() 
.addClass(org.javabydeveloper.domain.Student.class)
.setProperty("hibernate.dialect", "org.hibernate.dialect.MySQL5Dialect")
.setProperty("hibernate.connection.datasource", "jdbc:mysql://localhost:3380/<dbname>")
.setProperty("hibernate.order_updates", "true");

Configuration in hibernate.cfg.xml (MySQL8): 

 <property name="connection.url">jdbc:mysql://localhost:3380/jpa_jbd?serverTimezone=UTC&useSSL=false</property>
<property name="connection.username">user</property>
<property name="connection.password">pass</property>
<property name="connection.driver_class">com.mysql.jdbc.Driver</property>
<property name="dialect">org.hibernate.dialect.MySQL8Dialect</property>

List of SQL Dialects in Hibernate

All of the Hibernate dialects are available in the org.hibernate.dialect package. Following is the popular List of SQL Dialects in Hibernate.

The hibernate.dialect property defines the specific Dialect class for your database. Although Hibernate can auto-detect it from the connection, explicitly setting it ensures better compatibility and correct behavior for the database version.