for building sequence

SequenceHelp.java

import static com.beiyanght.jpa.ThreadLocalEntityManager.em;

import java.math.BigDecimal;

/**
 * 
 * @author  keating_andy_given
 */
public class SequenceHelp {
	
	/**
	 * 获取ID
	 */
	public static int computeId(int increaseSize, String keyName) {
		BigDecimal value = null;
		try {
			value = (BigDecimal) em().createNativeQuery(
					"select t.gen_value from ID_SEQUENCE t where t.keyid='"
							+ keyName + "'").getSingleResult();
		}catch(javax.persistence.NoResultException e) {
			em().createNativeQuery(
					"insert into ID_SEQUENCE(keyid,GEN_VALUE) values('"
							+ keyName + "','" + increaseSize + "')")
					.executeUpdate();
			return increaseSize;
		}
		em().createNativeQuery(
				"update ID_SEQUENCE set GEN_VALUE = '"
						+ (value.toBigInteger().longValue() + increaseSize)
						+ "' where keyid='" + keyName + "'").executeUpdate();
		return value.toBigInteger().intValue() + increaseSize;
	}
}