public static Dialect buildDialect(Properties properties) 
{
		String dialectName = properties.getProperty( Environment.DIALECT );
		if ( dialectName == null ) {
			throw new HibernateException( "'hibernate.dialect' must be set when no Connection avalable" );
		}
		return constructDialect( dialectName );
}

 public static Dialect buildDialect(Properties properties,
    Connection connection) throws HibernateException 
{
		String dialectName = properties.getProperty( Environment.DIALECT );
		if ( dialectName == null ) {
			return determineDialect( connection );
		}
		else {
			return constructDialect( dialectName );
		}
}

Builds an appropriate Dialect instance.

If a dialect is explicitly named in the incoming properties, it is used. Otherwise, it is determined by dialect resolvers based on the passed connection.

An exception is thrown if a dialect was not explicitly set and no resolver could make the determination from the given connection.

 public static Dialect constructDialect(String dialectName) 
{
		try {
			return ( Dialect ) ReflectHelper.classForName( dialectName ).newInstance();
		}
		catch ( ClassNotFoundException cnfe ) {
			throw new HibernateException( "Dialect class not found: " + dialectName, cnfe );
		}
		catch ( Exception e ) {
			throw new HibernateException( "Could not instantiate dialect class", e );
		}
}

Returns a dialect instance given the name of the class to use.

 static  void registerDialectResolver(String resolverName) 
{
	 
		// register the standard dialect resolver
		DIALECT_RESOLVERS.addResolver( new StandardDialectResolver() );
		// register resolvers set via Environment property
		String userSpecifedResolverSetting = Environment.getProperties().getProperty( Environment.DIALECT_RESOLVERS );
		if ( userSpecifedResolverSetting != null ) {
			String[] userSpecifedResolvers = userSpecifedResolverSetting.split( "\\s+" );
			for ( int i = 0; i <  userSpecifedResolvers.length; i++ ) {
				registerDialectResolver( userSpecifedResolvers[i] );
			}
		}
		try {
			DialectResolver resolver = ( DialectResolver ) ReflectHelper.classForName( resolverName ).newInstance();
			DIALECT_RESOLVERS.addResolverAtFirst( resolver );
		}
		catch ( ClassNotFoundException cnfe ) {
			log.warn( "Dialect resolver class not found: " + resolverName );
		}
		catch ( Exception e ) {
			log.warn( "Could not instantiate dialect resolver class", e );
		}
}