BetterHSQLDialect.java

/*
 * Copyright 2018 Global Crop Diversity Trust
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.genesys.blocks.util;

import java.sql.Types;

import org.hibernate.dialect.HSQLDialect;
import org.hibernate.dialect.function.SQLFunctionTemplate;
import org.hibernate.dialect.function.StandardSQLFunction;
import org.hibernate.type.DoubleType;
import org.hibernate.type.StandardBasicTypes;

/**
 * Hibernate's HSQL dialect uses clob(255) when length is not specified.
 *
 * Example: For JDBC connection to
 * <code>jdbc:hsqldb:mem:catalog;sql.syntax_mys=true;sql.ignore_case=true</code>
 * set Hibernate dialect to
 * <code>org.genesys.blocks.util.BetterHSQLDialect</code>.
 */
public class BetterHSQLDialect extends HSQLDialect {

	/**
	 * Instantiates a new better HSQL dialect.
	 */
	// http://stackoverflow.com/questions/12876551/hibernate-4-1-with-hsqldb-gives-data-exception-string-data-right-truncation
	public BetterHSQLDialect() {
		super();
		registerColumnType(Types.CLOB, "clob");
		registerColumnType(Types.BLOB, "blob");
		registerColumnType(Types.TIMESTAMP, "timestamp(8)");

		registerFunction("stddev", new StandardSQLFunction("stddev_pop", DoubleType.INSTANCE));
		registerKeyword("day"); // Needed for DATEDIFF(DAY, ...)
		registerFunction("datediff", new SQLFunctionTemplate(StandardBasicTypes.INTEGER, "datediff('day', ?1, ?2)"));

		// Needed for OFFSET 0 ROWS FETCH FIRST 1 ROWS ONLY
		registerKeyword("OFFSET");
		registerKeyword("FETCH");
		registerKeyword("FIRST");
		registerKeyword("ROWS");
		registerKeyword("ONLY");
	}
}